1. UNIT - 5 FUNCTIONS AND POINTERS

2. FUNCTION Functions is a sub-program that contains one or more statements and it performs some task when called.

3. Types Functions User-Defined Functions Pre-Defined Functions

4. Pre-Defined Functions The pre-defined functions or library functions are built-in functions. The user can use the functions, but cannot modify the function. Example: sqrt()

5. User-Defined Functions The functions defined by the user for their requirement are called user-defined functions. Whenever it is needed, The user can modify the function. Example: sum(a,b)

6. Advantage of User-Defined Functions The length of the source program can be reduced. It is easy to locate error. It avoid coding of repeated instructions.

7. Elements of User-Defined Function Function declaration Function definition Function call

8. Function Syntax datatype function_name (parameters list) { local variable declaration; ………………………… body of the function; ………………………… return(expression); }

9. How Function Works Once a function is called the control passes to the called function. The working of calling function is temporarily stopped. When the execution of called function is completed then the control return back to the calling function and execute the next statement.

11. Parameters Actual Parameter These are the parameters transferred from the calling function to the called function. Formal Parameter These are the parameters which is used in the called function.

13. return Statement The return statement may or may not send some values to the calling function. Syntax: return; (or) return(expression);

14. Function Prototypes Function with no arguments and no return values. Function with arguments and no return values. Function with arguments and return values. Function with no arguments and with return values.

15. Function with no arguments and no return values Here no data transfer take place between the calling function and the called function. These functions act independently, i.e. they get input and display output in the same block.

17. Example #include void main() //calling function { void add(void); add(); } void add()//called function { int a,b,c; printf("\nEnter two number:"); scanf("%d%d",&a,&b); c=a+b; printf("\nSum is:%d",c); }

18. Output Enter two number:3 4 Sum is:7

19. Function with arguments and no return values Here data transfer take place between the calling function and the called function. It is a one way data communication, i.e. the called program receives data from calling program but it does not return any value to the calling program.

21. Example #include void main() { int a,b; void add(int,int); printf("\nEnter two number:"); scanf("%d%d",&a,&b); add(a,b); } void add(int x,int y) //function with arguments { int z; z=x+y; printf("\nSum is:%d",z); }

22. Output Enter two number:2 4 Sum is:6

23. Example #include void main() { int a,b; void add(int a,int b); printf("\nEnter two number:"); scanf("%d%d",&a,&b); add(a,b); } void add(int x,int y) //function with arguments { int z; z=x+y; printf("\nSum is:%d",z); }

24. Output Enter two number:2 4 Sum is:6

25. Function with arguments and return values Here data transfer take place between the calling function and the called function as well as between called function and calling function. It is a two way data communication, i.e. the called program receives data from calling program and it return some value to the calling program.

27. Example #include void main() { int a,b,c; int add(int,int); printf("\nEnter two number:"); scanf("%d%d",&a,&b); c=add(a,b); printf("\nSum is:%d",c); } int add(int x,int y) { int z; z=x+y; return(z); }

28. Output Enter two number:6 7 Sum is:13

29. Function with no arguments and with return values Here data transfer take place between the called function and the calling function. It is a one way data communication, i.e. the called program does not receives data from calling program but it return some value to the calling program.

31. #include void main() { int add(),d; d=add(); printf("\nSum is:%d",d); } int add() //function wit no argument { int a,b,c; printf("\nEnter two number:"); scanf("%d%d",&a,&b); c=a+b; return(c); }

32. Output Enter two number:5 8 Sum is:13

33. Parameter Passing Methods Call by value Call by reference

34. Call by value Actual argument passed to the formal argument. Any changes to the formal argument does not affect the actual argument.

35. Example #include void main() { int x,y,change(int,int); printf("\nEnter value of x:"); scanf("%d",&x); printf("\nEnter value of y:"); scanf("%d",&y);

36. change(x,y); printf("\n\nValues in the Main()-->x=%d,y=%d",x,y); } int change(int a,int b) { int c; c=a; a=b; b=c; printf("\nValues in the Fuction -->x=%d,y=%d",a,b); }

37. Output Enter value of x:5 Enter value of y:6 Values in the Fuction -->x=6,y=5 Values in the Main()-->x=5,y=6

38. Call by reference Instead of passing value, the address of the argument will be passed. Any changes to the formal argument will affect the actual argument.

39. Example #include void main() { int x,y,change(int*,int*); printf("\nEnter value of x:"); scanf("%d",&x); printf("\nEnter value of y:"); scanf("%d",&y);

40. change(&x,&y); printf("\n\nValues in the Main()-->x=%d,y=%d",x,y); } int change(int *a,int *b) { int c; c=*a; *a=*b; *b=c; printf("\nValues in the Function -->x=%d,y=%d",*a,*b); }

41. Output Enter value of x:5 Enter value of y:6 Values in the Function -->x=6,y=5 Values in the Main()-->x=6,y=5

42. Recursion It is a process of calling the same function itself again and again until some condition is satisfied. Syntax: func1() { ……….. func1(); }

43. Example #include void main() { int a; int rec(int); printf("\nEnter the number:"); scanf("%d",&a); printf("The factorial of %d! is %d",a,rec(a)); }

44. int rec(int x) { int f; if(x==1) return(1); else f=x*rec(x-1); return(f); } Output: Enter the number:5 The factorial of 5! is 120

45. Example: Working of 3!

46. Tower of Honoi 1 2 3 32 3 1 3 2 3

47. 1 2 3 32 3 1 3 2 3

48. Library Function It is pre-defined function. The library function provides functions like mathematical, string manipulation etc,.

49. Example sqrt(x): It is used to find the square root of x Example: sqrt(36) is 6 abs(x): It is used to find the absolute value of x Example: abs(-36) is 36 pow(x,y): It is used to find the value of x y Example: pow(5,2) is 25 ceil(x): It is used to find the smallest integer greater than or equal to x Example: ceil(7.7) is 8

50. rand(): It is used to generate a random number. sin(x): It is used to find the sine value of x Example: sin(30) is 0.5 cos(x): It is used to find the cosine value of x Example: cos(30) is 0.86 tan(x): It is used to find the tan value of x Example: tan(30) is 0.577

51. toascii(x): It is used to find the ASCII value of x Example: toascii(a) is 97 toupper(x): It is used to convert lowercase character to uppercase. Example: toupper(‘a’) is A toupper(97) is A tolower(x): It is used to convert uppercase character to lowercase. Example: tolower(‘A’) is a

52. Example: #include void main() { int x,y=2; printf("\nEnter the number:"); scanf("%d",&x); printf("\nThe squareroot of %d is %f",x,sqrt(x)); printf("\nThe value of %d power%dis%f ",x,y,pow(6,2));

53. printf("\nThe ceiling of 6.7 is %f",ceil(6.7)); printf("\nThe floor of 6.7 is %f",floor(6.7)); printf("\nThe absolute value of -6 is %d",abs(-6)); printf("\nThe value of sin 45 is %f",sin(45)); printf("\nThe uppercase of 'a' is %c",toupper('a')); printf("\nThe uppercase of 97 is %c",toupper(97)); getch(); }

54. Output: Enter the number:6 The squareroot of 6 is 2.449490 The value of 6 power 2 is 36.000000 The ceiling of 6.7 is 7.000000 The floor of 6.7 is 6.000000 The absolute value of -6 is 6 The value of sin 45 is 0.850904 The uppercase of 'a' is A The uppercase of 97 is A

55. Array An Array is a collection of similar data items, that are stored under a common name. Types –One-Dimensional array –Two-Dimensional array – Multi-Dimensional array

56. One-Dimensional array Array Declaration Syntax: data_type array_name[size]; Example: int x[3]; X[0] X[1] X[2] x

57. Array initialization At compile time At run time

58. At compile time Syntax: data_type array_name[size]={variables}; Example: int x[3]={5,3,7}; 5 3 7 X[0] X[1] X[2] x

59. At Run time Array can also initialize at the run time. Example: while(i<10) { if(i<5) sum[i]=0; else sum[i]=sum[i]+i; }

60. Example: scanf(“%d%d”,&a[0],&a[1]);

61. Example #include void main() { int x[2],i; printf("\nEnter the inputs:"); for(i=0;i<2;i++) scanf("%d",&x[i]); for(i=0;i<2;i++) printf("\nThe value in x[%d] is %d",i,x[i]); getch(); }

62. Output Enter the inputs:3 6 The value in x[0] is 3 The value in x[1] is 6

63. Example #include void main() { int i; char x[5]={'a','b','c','d','e'}; clrscr(); for(i=0;i<5;i++) printf("\nThe value in x[%d] is %c",i,x[i]); getch(); }

64. Output The value in x[0] is a The value in x[1] is b The value in x[2] is c The value in x[3] is d The value in x[4] is e

65. Two-Dimensional array Array Declaration Syntax: data_type array_name[row_size] [col_size]; Example: int x[3][2]; X[0][0] X[1][0] X[2][0] Col 0 Col 1 row 0 row 1 row 2 X[0][1] X[1][1] X[2][1]

66. Array Initialization Syntax: data_type array_name[row_size] [col_size];={variables}; Example: int x[2][2]={1,50,2,75};

67. int x[2][2]={ {1,50}, {2,75} }; (or) int x[ ][2]={ {1,50}, {2,75} };

68. 150 275 row 0 row 1 Col 0 Col 1

69. Example #include void main() { int i,j; int x[2][2]={{1,50}, {2,75} }; clrscr(); for(i=0;i<2;i++) for(j=0;j<2;j++) printf("\nThe value in x[%d][%d] is %d",i,j,x[i][j]); getch(); }

70. Output The value in x[0][0] is 1 The value in x[0][1] is 50 The value in x[1][0] is 2 The value in x[1][1] is 75

71. Example #include void main() { int i,j; int x[][2]={ {1,50},{2,75},{3,65}}; clrscr(); for(i=0;i<=2;i++) for(j=0;j<2;j++) printf("\nThe value in x[%d][%d] is %d",i,j,x[i][j]); getch(); }

72. Output The value in x[0][0] is 1 The value in x[0][1] is 50 The value in x[1][0] is 2 The value in x[1][1] is 75 The value in x[2][0] is 3 The value in x[2][1] is 65

73. Matrix Addition #include void main() { int i,j,k,r1,r2,c1,c2; int a[5][5],b[5][5],c[5][5]; clrscr(); step1: printf("\n Enter the size of matrix A:"); scanf("%d%d",&r1,&c1); printf("\n Enter the size of matrix B: "); scanf("%d%d",&r2,&c2); if((c1==c2)&&(r1==r2)) goto step2; else goto step1;

74. step2: printf("\n Enter the elements of matrix A \n"); for(i=0;i<r1;i++) { for(j=0;j<c1;j++) { scanf("%d",&a[i][j]); } printf("\n Enter the elements of matrix B \n"); for(i=0;i<r2;i++) { for(j=0;j<c2;j++) { scanf("\t%d",&b[i][j]); }

75. for(i=0;i<r1;i++) { for(j=0;j<c1;j++) { c[i][j]=0; c[i][j]=c[i][j]+a[i][j]+b[i][j]; } printf("\n The resultant matrix after addition of A & B is\n"); for(i=0;i<r1;i++) { for(j=0;j<c1;j++) printf("%d\t",c[i][j]); printf("\n"); } getch(); }

76. Output Enter the size of matrix A: 2 2 Enter the size of matrix B: 2 2 Enter the elements of matrix A 2 Enter the elements of matrix B 3 The resultant matrix after addition of A&B is 5

77. Matrix Multiplication #include void main() { int i,j,k,r1,r2,c1,c2; int a[5][5],b[5][5],c[5][5]; clrscr(); step1: printf("\n Enter the size of matrix A \n"); scanf("%d%d",&r1,&c1); printf("\n Enter the size of matrix B \n"); scanf("%d%d",&r2,&c2); if(c1==r2) goto step2; else goto step1;

78. step2: printf("\n Enter the elements of matrix A \n"); for(i=0;i<r1;i++) { for(j=0;j<c1;j++) { scanf("%d",&a[i][j]); } printf("\n Enter the elements of matrix B \n"); for(i=0;i<r2;i++) { for(j=0;j<c2;j++) { scanf("\t%d",&b[i][j]); }

79. for(i=0;i<r1;i++) { for(j=0;j<c2;j++) { c[i][j]=0; for(k=0;k<c1;k++) { c[i][j]=c[i][j]+a[i][k]*b[k][j]; } for(i=0;i<r1;i++) { for(j=0;j<c2;j++) printf("%d\t",c[i][j]); printf("\n"); } getch(); }

80. Output Enter the size of matrix A:2 2 Enter the size of matrix B:2 2 Enter the elements of matrix A 4 Enter the elements of matrix B 4 The resultant matrix is 32

81. Enter the size of matrix A:2 3 Enter the size of matrix B:3 2 Enter the elements of matrix A 1 2 3 4 5 6 Enter the elements of matrix B 2 4 6 8 2 4

82. 20 32 50 80

83. Passing array to Function Here an array is transferred as parameter to a function. void main() void fun(n,b[]) { void fun(int,int);int x,b[5]; int a[5],n;………….. ……………………….. fun(n,a); …………… } }

84. Example #include void add(int,int b[]); void main() { int a[5],i,n; clrscr(); printf("\n Enter the Number: "); scanf("%d",&n); printf("\n Enter the Values: "); for(i=0;i<n;i++) scanf("%d",&a[i]); add(n,a); }

85. void add(int x,int b[]) { int sum=0,i; for(i=0;i<x;i++) sum=sum+b[i]; printf("\nThe sum is: %d",sum); }

86. Output Enter the Number: 5 Enter the Values: 1 2 3 4 5 The sum is: 15

87. Array of Characters In array the characters are terminated by the null (‘\0’) character. Example: char a[]={a,b,c}; abc\0

88. Example #include void main() { int i=0; char a[]="abcd"; clrscr(); while(a[i]!='\0') { printf("\t%c",a[i]); i++; }

89. Output a b c d

90. Multi Dimensional Array Syntax datatype array_name [size1][size2]….[size n] datatype- type of the data. array_name-name of the array. size-size of the array.

91. Example: int a[3][3][3]; Col 0 Col 1 Col 2 row 0 row 1 row 2 X[0][0] X[1][0] X[2][0] X[0][1] X[1][1] X[2][1] X[0][2] X[1][2] X[2][2]

92. String Functions strlen() It is used to find the length of the string. syntax: strlen(string) strcpy() It is used to copy one string to another. syntax: strcpy(string1,string2) strcat() It is used to combine two strings. syntax: strcat(string1,string2)

93. strcmp() It is used to compare two strings. syntax: strcmp(string1,string2) –Returns 0 if two strings are equal. –Return value <0 if s1 is less than s2. –Return value >0 if s1 is greater than s2. strrev() It used to reverse a string. syntax: strrev(string) strlwr(), strupr() It used to change the case of a string. syntax: strlwr(string) strupr(string)

94. strncpy() It used to copy ‘n’ characters of one string to another. strstr() –It is used to determine the first occurrence of a given string in another string. strncat() –It Appends source string to destination string upto specified length. strspn() –It is used t find upto what length two strings are identical.

95. strncmp() – It is used to compare ‘n’ character of two strings. strcmpi() – It is used to compare two strings without regarding the case. strnicmp() – It is used to compare first ‘n’ characters of two strings without regarding the case. strchr() – It is used to determine the first occurrence of a given character in a string. strrchr() – It is used to determine the last occurrence of a given character in a string.

96. Example #include void main() { char a[]="college"; int b; clrscr(); b=strlen(a); printf("\nThe length of the string is %d",b); getch(); } Output: The length of the string is 7

97. Example #include void main() { char a[]="IT"; char b[]="Dept"; clrscr(); strcpy(a,b); printf("\nThe string is %s",a); getch(); } Output: The string is Dept

98. Example #include void main() { char a[]="IT"; char b[]="Dept"; clrscr(); strcat(a,b); printf("\nThe string is %s",a); getch(); } Output: The string is ITDept

99. Example #include void main() { char a[]="itdept"; char b[]="it"; int i; clrscr(); i=strcmp(a,b); if(i==0) printf("\nstrings are equal:%d",i); else if(i<0) printf("\nstring1 is less than string2:%d",i);

100. else printf("\nstring1 is greater than string2:%d",i); getch(); } Output: string1 is greater than string2:100

101. Example #include void main() { char a[]="itdept"; clrscr(); printf("\nThe string is :%s",a); strupr(a); printf("\nThe string after conversion to uppercase :%s",a); strlwr(a); printf("\nThe string after conversion to lowercase :%s",a); getch(); }

102. Output The string is :itdept The string after conversion to uppercase :ITDEPT The string after conversion to lowercase :itdept

103. Example #include void main() { char a[]="Dept"; clrscr(); printf("\nThe string is %s",strrev(a)); getch(); } Output: The string is tpeD

104. Example #include void main() { char a[]="itdept"; char b[15]; int i=0; clrscr(); strncpy(b,a,2); b[2]='\0'; printf("\nThe string is :%s",b); getch(); }

105. Output: The string is :it

106. String Palindrome #include void main() { int len,i,j; char str[15]; clrscr(); printf("\n Enter the string:"); scanf("%s",str); len=strlen(str);

107. for(i=0,j=len-1;i<len/2;i++,j--) { if(str[i]!=str[j]) { printf("\nThe String is not a palindrome"); getch(); exit(0); } printf("\nThe String is a palindrome"); getch(); } Output: Enter the string:abcba The String is a palindrome

108. Enumerated Data Type It is user defined data type. The user can create their own data type and define some values to the variables. Syntax: enum tag_name { enum1; enum2; ………. };

109. Example #include void main() { enum week {sun,mon,tue,wed,thr,fri,sat}; clrscr(); printf("\nMonday=%d",mon); printf("\nSaturday=%d",sat); getch(); } Output: Monday=1 Saturday=6

110. Example #include void main() { enum week {sun=10,mon,tue,wed,thr,fri,sat}; clrscr(); printf("\nMonday=%d",mon); printf("\nsaturday=%d",sat); getch(); } Output: Monday=11 saturday=16

111. Structure A Structure is a collection of different data items, that are stored under a common name. Syntax: struct structure_name { structure element1; structure element2; ……………………. };

112. Example: struct stud { int sno; char name[10]; int mark; }; struct stud s;

113. Example #include struct stud { int regno; char name[10]; int m1; int m2; int m3; }; struct stud s; void main() { float tot,avg;

114. printf("\nEnter the student regno,name,m1,m2,m3:"); scanf("%d%s%d%d%d",&s.regno,&s.name,&s.m1,&s.m2, &s.m3); tot=s.m1+s.m2+s.m3; avg=tot/3; printf("\nThe student Details are:"); printf("\n%d\t%s\t%f\t%f",s.regno,s.name,tot,avg); }

115. Output Enter the student regno,name,m1,m2,m3:100 aaa 87 98 78 The student Details are: 100 aaa 263.000000 87.666664

116. Structure assignment It is possible to assign one structure information to another structure of same type using simple assignment statement.

117. Example #include void main() { struct { int a; }x,y; clrscr(); x.a=10; y=x; printf("The value of y.a is%d",y.a); getch(); }

118. Output The value of y.a is10

119. Example #include struct stud { int regno; char name[10],grade; int m1,m2,m3; float avg,tot; } s[10]; void main() { int i,n; printf("\nEnter the no.of students:"); scanf("%d",&n);

120. for(i=0;i<n;i++) { printf("\nEnter the student regno,name,m1,m2,m3:"); scanf("%d%s%d%d%d",&s[i].regno,&s[i].name,&s[i].m1, &s[i].m2,&s[i].m3); s[i].tot=s[i].m1+s[i].m2+s[i].m3; s[i].avg=s[i].tot/3; if(s[i].m1<35||s[i].m2<35||s[i].m3<35) s[i].grade='f'; else { if(s[i].avg>=75) s[i].grade='d'; else if(s[i].avg>=60)

121. s[i].grade='A'; else if(s[i].avg>=50) s[i].grade='B'; else if(s[i].avg>=35) s[i].grade='C'; } printf("\nSTUDENT MARK LIST\n"); printf("\nREGNO\tNAME\tTOTAL\tAvg\tGRADE"); for(i=0;i<n;i++) printf("\n%d\t%s\t%f\t%f\t%c",s[i].regno,s[i].name,s[i].tot, s[i].avg,s[i].grade); getch(); }

122. Enter the no.of students:2 Enter the student regno,name,m1,m2,m3:101 aaa 89 98 78 Enter the student regno,name,m1,m2,m3:102 bbb 59 68 76 STUDENT MARK LIST REGNO NAME TOTAL Avg GRADE 101 aaa 265.000000 88.333336 d 102 bbb 203.000000 67.666664 A

123. Union An Union is a collection of different data items, that are stored under a common name. Here same memory is shared by its members. Syntax: union union _name { union element1; union element2; ………………… };

124. Example: union result { int mark; float avg; char grade; }; union result s;

125. Example #include union stud { int a; char b[2]; }; void main() { union stud c;

126. c.a=256; printf("\nc.a value is%d",c.a); printf("\nc.b[0] value is%d",c.b[0]); printf("\nc.b[1] value is%d",c.b[1]); } Output: c.a value is256 c.b[0] value is0 c.b[1] value is1

127. 256 = 00000010 00000000 Higher bit Lower bit 00000000 00000010 c.a - 2 Byte c.b[0] 1 Byte c.b[0]c.b[1]

128. Example #include struct student { int a; int b; char c; }s; union student1 { int a; int b; char c; }s1;

129. void main() { printf("\nThe size of struct is %d",sizeof(s)); printf("\nThe size of union is %d",sizeof(s1)); getch(); } Output: The size of struct is 5 The size of union is 2

130. Structure & Union int int char 2 Byte 2Byte 1Byte 2 Byte structure int,int, char union

131. Preprocessor It is a program that processes the source program before compilation. It operates under the following directives – File Inclusion – Macro substitution – Conditional inclusion

132. File Inclusion It is used to include some file that contains functions or some definitions. Syntax: #include (or) #include“filename” Eg: #include #include “ex.c”

133. Example #include #include "addition.txt" void main() { int a,b; printf("\nEnter the numbers:"); scanf("%d%d",&a,&b); printf("The Value is %d",add(a,b)); getch(); }

134. addition.txt int add(int a,int b) { return(a+b); }

135. Output Enter the numbers:7 4 The Value is 11

136. Example #include #include "fact.c" void main() { int a; printf("\nEnter the number:"); scanf("%d",&a); printf("The factorial of %d! is %d",a,rec(a)); getch(); }

137. fact.c int rec(int x) { int f; if(x==1) return(1); else f=x*rec(x-1); return(f); }

138. Output Enter the number:5 The factorial of 5! is 120

139. Macro Substitution It is used to define and use integer, string, or identifier in the source program The three forms of macros are – Simple Macro – Argumented Macro – Nested Macro

140. Simple Macro It is used to define some constants Syntax # define identifier string/integer Eg: #define pi 3.14 #define CITY “chennai”

141. Example #include #define pi 3.14 #define CITY "chennai" void main() { printf("The Value is %f",2*pi); printf("\nThe Value CITY is %s",CITY); getch(); } Output: The Value is 6.280000 The Value CITY is chennai

142. Argumented Macro It is used to define some complex forms in the source program. Syntax: #define identifier (v1,v2,….) string/integer Eg: #define cube(n) (n*n*n)

143. Example #include #define cube(n) (n*n*n) void main() { printf("The Value of 3 cube is %d",cube(3)); getch(); } Output: The Value of 3 cube is 27

144. Nested Macro Here one macro is used by another macro. Eg: #define a 3 #define sq a*a

145. Example #include #define a 3 #define sq a*a void main() { printf("The Value is %d",sq); getch(); } Output: The Value is 9

146. Conditional Inclusion It is used to include some conditional statements.

147. Example #include #define a 3 #ifdef a #define c a+5 #endif void main() { printf("\nThe value C is %d",c); getch(); } Output: The value C is 8

148. Pointers Pointer is a variable that contains the memory address of another variable.

149. Example: x=5 x Variable 1002 Address 5 Value

150. Example #include void main() { int x=5; printf("\n The Address of x = %u",&x); printf("\n The Value of x = %d",x); } Output The Address of x = 8714 The Value of x = 5

151. Pointer Declaration Syntax data-type *pointer-name; data-type - Type of the data to which the pointer points. pointer-name - Name of the pointer Example: int *a;

152. Accessing Variable through Pointer If a pointer is declared and assigned to a variable, then the variable can be accessed through the pointer. Example: int *a; x=5; a=&x;

153. Example #include void main() { int x=5; int *a; a=&x; printf("\n The Value of x = %d",x); printf("\n The Address of x = %u",&x); printf("\n The Value of a = %d",a); printf("\n The Value of x = %d",*a); }

154. Output The Value of x = 5 The Address of x = 8758 The Value of a = 8758 The Value of x = 5

155. Example: #include void main() { int y=10; int *a; a=&y; printf("\n The Value of y = %d",y); printf("\n The Address of y = %u",&y); printf("\n The Value of a = %d",a); printf("\n The Address of a = %u",&a); }

156. 500110 8000 ay 5001 Variable Value Address

157. Output The Value of y = 10 The Address of y = 5001 The Value of a = 5001 The Address of a = 8000

158. Null Pointer A pointer is said to be null pointer if zero is assigned to the pointer. Example int *a,*b; a=b=0;

159. Pointer to Pointer Here one pointer stores the address of another pointer variable. Example: int x=10,*a,**b; a=&x; b=&a;

160. 500110 8000 ax 5001 Variable Value Address 8000 9000 b

161. Example #include void main() { int a=10; int *b,**c; b=&a; c=&b; printf("\n The Value of a = %d",a); printf("\n The Address of a = %u",&a); printf("\n The Value of b = %d",b); printf("\n The Address of b = %u",&b); printf("\n The Value of c = %d",c); printf("\n The Address of c = %u",&c); }

162. Output The Value of a = 10 The Address of a = 5001 The Value of b = 5001 The Address of b = 8000 The Value of c = 8000 The Address of c = 9000

163. Pointers and Functions Call by Value Call by Reference

164. Call by value Actual argument passed to the formal argument. Any changes to the formal argument does not affect the actual argument.

165. Example #include void main() { int x,y,swap(int,int); printf("\nEnter value of x:"); scanf("%d",&x); printf("\nEnter value of y:"); scanf("%d",&y);

166. change(x,y); printf("\n\nValues in the Main()-->x=%d,y=%d",x,y); } int swap(int a,int b) { int c; c=a; a=b; b=c; printf("\nValues in the Function -->x=%d,y=%d",a,b); }

167. Output Enter value of x:5 Enter value of y:6 Values in the Function -->x=6,y=5 Values in the Main()-->x=5,y=6

169. Call by reference Instead of passing value, the address of the argument will be passed. Any changes to the formal argument will affect the actual argument.

170. Example #include void main() { int x,y,change(int*,int*); printf("\nEnter value of x:"); scanf("%d",&x); printf("\nEnter value of y:"); scanf("%d",&y);

171. change(&x,&y); printf("\n\nValues in the Main()-->x=%d,y=%d",x,y); } int change(int *a,int *b) { int c; c=*a; *a=*b; *b=c; printf("\nValues in the Function -->x=%d,y=%d",*a,*b); }

172. Output Enter value of x:5 Enter value of y:6 Values in the Function -->x=6,y=5 Values in the Main()-->x=6,y=5

173. Pointer to Array The elements of the array can also be accessed through a pointer. Example int a[3]={2,3,7}; int *b; b=a;

174. Example: #include void main() { int a[3]={2,3,7}; int *b; b=a; printf("\n The Value of a[0] = %d",a[0]); printf("\n The Address of a[0] = %u",&a[0]); printf("\n The Value of b = %d",b); }

175. 87442 9000 ba[0] 8744 Variable Value Address

176. Output The Value of a[0] = 2 The Address of a[0] = 8744 The Value of b = 8744

177. Example #include void main() { int a[5]={2,3,7,9,10}; int i; for(i=0;i<5;i++) { printf("\n The Value of a[%d] = %d",i,a[i]); printf("\n The Address of a[%d] = %u",i,&a[i]); }

178. 237910 a[0] a[1]a[2] a[3] a[4] 8724 8726 8728 8730 8732 Array Value Address

179. Output The Value of a[0] = 2 The Address of a[0] = 8724 The Value of a[1] = 3 The Address of a[1] = 8726 The Value of a[2] = 7 The Address of a[2] = 8728 The Value of a[3] = 9 The Address of a[3] = 8730 The Value of a[4] = 10 The Address of a[4] = 8732

180. Example #include void main() { int a[5]={1,2,3,4,5}; int i,sum=0; int *b; b=a; for(i=0;i<5;i++) { sum=sum + *b; b++;//b=b+1 } printf("\n The Sum is %d",sum); }

181. Output The Sum is 15

182. Pointer and Structures Syntax: struct structure_name { structure element1; structure element2; ……………………. }variable,*ptr;

183. Example: struct stud { int sno; char name[10]; int mark; }; struct stud *s;

184. Example #include struct stud { int regno; char name[10]; int m1; int m2; int m3; }; struct stud s; struct stud *t;

185. void main() { float tot,avg; t=&s; printf("\nEnter the student regno,name,m1,m2,m3:"); scanf("%d%s%d%d%d",&s.regno,&s.name,&s.m1,&s.m2,& s.m3); tot=s.m1+s.m2+s.m3; avg=tot/3; printf("\nThe student Details are:"); printf("\n%d\t%s\t%f\t%f",s.regno,s.name,tot,avg); printf("\n%d\t%s\t%f\t%f",t->regno,t->name,tot,avg); }

186. Output Enter the student regno,name,m1,m2,m3:1 aaa 76 89 76 The student Details are: 1 aaa 241.000000 80.333336

187. Command Line Argument It allows the user to pass some information to the program while running the program.

188. Example #include void main(int argc,char argv[]) { printf("\n The Argument is %s",argv[0]); getch(); }

189. Output C:\tc>a The Argument is C:\TC\A.EXE

190. String Palindrome #include void main() { char s1[15],s2[15]; printf("\nenter the string:"); scanf("%s",s1); strcpy(s2,s1); strrev(s1);

191. if(strcmp(s1,s2)==0) printf("\n The string is palindrome"); else printf("\n The string is not a palindrome"); getch(); } Output: enter the string: aba The string is palindrome

192. Developing a ‘C’ Program The Program development life cycle is considered as a sequence of events by the programmer to develop the program. The Program development life cycle contains the following phase – Program Design – Program Coding – Program Testing

193. Program Design Analysing the problem Algorithm development Selection of conditional and control structure etc,.

194. Program Coding Documentation Statement construction Input and output format etc,.

195. Program Testing It is the process of executing the program with sample data

197. Example #include #define p 3.14 void main() { #ifdef p printf("\nPentium"); #else printf("\n Celeron"); #endif printf("\nthe value is %f",2*p); getch(); } Output: Pentium the value is 6.280000

199. Example #include struct stud { int regno; char name[10]; int m1; int m2; int m3; }; struct stud s; void main() { float tot,avg; int i;

200. printf("\nEnter the student regno,name,m1,m2,m3:"); for(i=0;i<2;i++) { scanf("%d%s%d%d%d",&s.regno,&s.name,&s.m1,&s.m 2,&s.m3); tot=s.m1+s.m2+s.m3; avg=tot/3; } for(i=0;i<2;i++) printf("%d\t%s\t%f\t%f",s.regno,s.name,tot,avg); }

201. Enter the student regno,name,m1,m2,m3:100 aaa 78 67 98 101 bbb 80 90 75 101bbb 245.000000 81.666664

202. #include int main(void) { char string[15]; char *ptr, c = 'r'; strcpy(string, "This is a string"); ptr = strchr(string, c); if (ptr) printf("The character %c is at position: %d\n", c, ptr- string); else printf("The character was not found\n"); return 0; }

203. Example #include void main() { char a[]="Dept"; int i=0; clrscr(); while(a[i]!='\0') { printf("\nThe character is %c",a[i]); i++; } getch(); }

204. The character is D The character is e The character is p The character is t

206. Structure

210. Lab Exercise C Programs

211. Function-with arg & return #include void main() { int a,b,c; int add(int,int); printf("\nEnter two number:"); scanf("%d%d",&a,&b); c=add(a,b); printf("\nSum is:%d",c); } int add(int x,int y) { int z; z=x+y; return(z); }

212. Output Enter two number:6 7 Sum is:13

213. Example #include void main() { int x,y,change(int*,int*); printf("\nEnter value of x:"); scanf("%d",&x); printf("\nEnter value of y:"); scanf("%d",&y);

214. change(&x,&y); printf("\n\nValues in the Main()-->x=%d,y=%d",x,y); } int change(int *a,int *b) { int c; c=*a; *a=*b; *b=c; printf("\nValues in the Function -->x=%d,y=%d",*a,*b); }

215. Output Enter value of x:5 Enter value of y:6 Values in the Function -->x=6,y=5 Values in the Main()-->x=6,y=5

216. Factorial-Recursive Fn #include void main() { int a; int rec(int); printf("\nEnter the number:"); scanf("%d",&a); printf("The factorial of %d! is %d",a,rec(a)); }

217. int rec(int x) { int f; if(x==1) return(1); else f=x*rec(x-1); return(f); } Output: Enter the number:5 The factorial of 5! is 120

218. Example: Working of 3!

219. Matrix Multiplication #include void main() { int i,j,k,r1,r2,c1,c2; int a[5][5],b[5][5],c[5][5]; clrscr(); step1: printf("\n Enter the size of matrix A \n"); scanf("%d%d",&r1,&c1); printf("\n Enter the size of matrix B \n"); scanf("%d%d",&r2,&c2); if(c1==r2) goto step2; else goto step1;

220. step2: printf("\n Enter the elements of matrix A \n"); for(i=0;i<r1;i++) { for(j=0;j<c1;j++) { scanf("%d",&a[i][j]); } printf("\n Enter the elements of matrix B \n"); for(i=0;i<r2;i++) { for(j=0;j<c2;j++) { scanf("\t%d",&b[i][j]); }

221. for(i=0;i<r1;i++) { for(j=0;j<c2;j++) { c[i][j]=0; for(k=0;k<c1;k++) { c[i][j]=c[i][j]+a[i][k]*b[k][j]; } for(i=0;i<r1;i++) { for(j=0;j<c2;j++) printf("%d\t",c[i][j]); printf("\n"); } getch(); }

222. Output Enter the size of matrix A:2 2 Enter the size of matrix B:2 2 Enter the elements of matrix A 4 Enter the elements of matrix B 4 The resultant matrix is 32

224. Lab Ex:9,Finding area, circumference of circle #include void main ( ) { int r; float area,c; clrscr( ); printf(" \nEnter the value of r:"); scanf("%d",&r);

225. area=3.14*r*r; c=2*3.14*r; printf(" \nThe area is :%f",area); printf(" \nThe circumference is :%f",c); getch( ); } Output: Enter the value of r:7 The area is :153.860001 The circumference is :43.959999

226. Lab Ex:9,Conversion of Celsius to Fahrenheit #include void main ( ) { float c,f; clrscr( ); printf(" \nEnter the value of c:"); scanf("%f",&c); f=(c*1.8)+32; printf(" \nThe Fahrenheit is :%f",f); getch( ); }

227. Enter the value of c:35 The fahrenheit is :95.000000

228. Lab Ex:11,Arithmetic operations #include void main() { int a,b,c,d,e,f; clrscr(); printf("\nEnter the values of A and B:"); scanf("%d%d",&a,&b); c=a+b; d=a-b; e=a*b; f=a/b;

229. printf("\nThe values of A + B:%d",c); printf("\nThe values of A - B:%d",d); printf("\nThe values of A * B:%d",e); printf("\nThe values of A / B:%d",f); getch(); }

230. Output Enter the values of A and B:6 3 The values of A + B:9 The values of A - B:3 The values of A * B:18 The values of A / B:2

231. Lab.Ex13,Largest among 3 nos #include void main ( ) { int a,b,c; clrscr( ); printf(" \nEnter the value of a:"); scanf("%d",&a); printf(" \nEnter the value of b:"); scanf("%d",&b); printf(" \nEnter the value of c:"); scanf("%d",&c);

232. if((a>b)&&(a>c)) { printf(" \nA is Big"); } else { if(b>c) printf(" \nB is Big"); else printf(" \nC is Big"); } getch( ); }

233. Output Enter the value of a:5 Enter the value of b:7 Enter the value of c:3 B is Big

234. String Palindrome #include void main() { int len,i,j; char str[15]; clrscr(); printf("\n Enter the string:"); scanf("%s",str); len=strlen(str);

235. for(i=0,j=len-1;i<len/2;i++,j--) { if(str[i]!=str[j]) { printf("\nThe String is not a palindrome"); getch(); exit(0); } printf("\nThe String is a palindrome"); getch(); } Output: Enter the string:abcba The String is a palindrome

236. Lab.Ex:14,Quadratic Equation #include void main ( ) { int a,b,c,d,r1,r2; clrscr( ); printf(" \nEnter the value of a:"); scanf("%d",&a); printf(" \nEnter the value of b:"); scanf("%d",&b); printf(" \nEnter the value of c:"); scanf("%d",&c); d=b*b-4*a*c;

237. if(d>=0) { r1=(-b+sqrt(d))/(2*a); r2=(-b-sqrt(d))/(2*a); printf(" \nThe roots are %d,%d",r1,r2); } else { printf(" \nThe roots are imaginary"); } getch( ); }

238. Output Enter the value of a:1 Enter the value of b:4 Enter the value of c:4 The roots are -2,-2