1. C Programming Input output Conditional statements and Iterative statements Rohit Khokher

2. Input & output in C Reading a Character from a keyboard – variable_name =getchar (); #include void main () { charx; x= getchar (); printf (“\n Input = %c”,x) } Writing a character one at a time to screen. – variable_name =putchar(); #include void main () { charx; x= getchar (); putchar (x}; putchar (‘\n’); }

3. Formatted Input Data represented in a format as shown below: A15.75 123 John Real number with two decimal digits Integer String %wd Format specification Field width Specifies a data to be read %f Specifies a real data to be read Character %wc %ws

4. scans (“format control string”, arg 1,arg 2, arg 3, …, arg n ) A 15.75 123 John char x; floaty; int z; charname[3]; scanf(“%c %f %d %s”, x, &y, &z, name); scanf accepts the address of y and z so we need & operator that gives the address of the variables y and z. String and character type declarations provide the address of the first character so we don’t need &.

5. %cRead a single character %dRead a decimal integer %fRead a floating point value %eRead a floating point value %gRead a floating point value %hRead a short integer %iRead a decimal, hexadecimal or octal integer %oRead an octal integer %sRead a string %uRead an unsigned decimal integer %xRead a hexadecimal integer %[..]Read a string of words Commonly used scanf format code

6. Formatted output scans (“format control string”, arg 1,arg 2, arg 3, …, arg n ) Display heading specification Display format specification Escape sequences \n, \t, \b “The out put of the program is” Integer %wd Real numbers %w.pf or w.pe where w>=p+7 String %w.ps or %wc

7. %cPrint a single character %dPrint a decimal integer %fPrint a floating point value %ePrint a floating point value %gPrint a floating point value %hPrint a short integer %iPrint a decimal, hexadecimal or octal integer %oPrint an octal integer %sPrint a string %uPrint an unsigned decimal integer %xPrint a hexadecimal integer Commonly used printf format code

8. Decision making & branching if statement Switch statement Conditional operator statement goto statement Simple if statement if …else statement Nested if …else statement else if ladder

9. Simple if statementExample General form if( test expression) { statement-block; }... … If ( a==b) { x=a*b+20; y=b/x; } …. ….. Decision making & branching

10. if …. else statement Example General form If ( test expression) { True -block; } Else { False-block; }... If ( a==b) { x=a*b+20; y=b/x; } else { z=a/b; } Decision making & branching

11. Nesting of if …. else statement if ( test expression 1) { if ( test expression 2) { True -block; } else { False-block; } else { } if ( A> B ) { if ( A>C) { printf ( “%f\n”,A);} else {printf ( “%f\n”,C);} else { if ( B>C) {printf ( “%f\n”,B);} else {printf ( “%f\n”,C); } }

12. if ( test expression 1) statement 1; else if ( test expression 2) statement 2; else if ( test expression 3) statement 3; else statement 4; The else if ladder if ( m > 79) printf(“\n Honours”); else if (m>59) printf(“\n First”); else if ( m>49) printf(“\n Second”); else printf(“\n Fail”);

13. The switch statement switch (expression) { case value : block; break; case value : block; break; ……………. …………….. default: block; break; } switch (i) { case 10 : block; break; case 9: block; break; default: block; break; } switch (ch) { case ‘A’ : block; break; case ‘B’: block; break; default: block; break; }

14. Iteration (Looping) sum =0; label: sum=sum+1; if (sum <5) { goto label; } Sum 0 1 2 3 4 5

15. While & do while while (expression) {...block of statements to execute... } do { block of code } while (condition is satisfied);

16. Example while & do while loop #include int main(void) { int loop = 0; while (loop <=10) { printf(“%d”, loop); ++loop } return 0; } #include int main(void) { int value, r_digit; printf(“enter a number to be reversed.\n”); scanf(%d, &value); do { r_digit = value % 10; printf(“%d”, r_digit); value = value / 10; } while (value != 0); printf(\n); return 0; }

17. Algorithm tracing.... value =986 do { r_digit = value % 10; printf(“%d”, r_digit); value = value / 10; } while (value != 0);............. valuer_digit 9866 988 99 0

18. For loop for (expression_1; expression_2;expression_3) {...block of statements to execute... } for (count = 1; count <=10; count = count +1) printf(“%d”, count); for (count = 1; count <=10; count = count + 1) { printf(“%d”, count); printf(“\n”); }

19. Example for loop #include int main(void) { int count; for (count = 1; count <=10; count = count + 1) printf(“%d”, count); printf(“\n”); return 0; }

20. Example for loop #include void main(){ // using for loop statement int max = 5; int i = 0; for(i = 0; i < max;i++) { printf("%d\n",i); }

21. Example do while #include void main(){ int x = 5; int i = 0; // using do while loop statement do{ i++; printf("%d\n",i); }while(i < x); }

22. Loop with break #include void main(){ int x = 10; int i = 0; // when number 5 found, escape loop body int numberFound= 5; int j = 1;. while(j < x){ if(j == numberFound){ printf("number found\n"); break; } printf("%d...keep finding\n",j); j++; } }