Presentation is loading. Please wait.

Presentation is loading. Please wait.

Structures Often we want to be able to manipulate logical entities as a whole For example, complex numbers, dates, student records, etc Each of these must.

Published byChaz Baptist Modified over 10 years ago

Similar presentations

Presentation on theme: "Structures Often we want to be able to manipulate logical entities as a whole For example, complex numbers, dates, student records, etc Each of these must."— Presentation transcript:

1 Structures Often we want to be able to manipulate logical entities as a whole For example, complex numbers, dates, student records, etc Each of these must be composed of more than one variable, but are logically units A struct (short for structure) is a collection of variables of different types, gathered into one super-variable It is used to define more complex data types Variables in a struct are called members or fields

2 Example – complex numbers. The following is the definition of a new variable of type complex number: struct complex { int real; int img; }; Once we define a structure, we can treat it as any type. In a program, we can then write: struct complex num1, num2, num3;

3 Access structure members If A is of some structure with a member named x, then A.x is that member of A struct complex C; C.real = 0; If A is a pointer to a structure with a member x, then A->x is that member of the variable pointed by A. This is simply shorthand for - (*A).x struct complex *pc = &C; pc->real = 1;

4 A more convenient usage with typedef An alternative definition: typedef struct complex_t { int real; int img; } complex; Now the program has a new variable type - complex. This way we dont have to write struct complex every time! For example, we can define two complex numbers in the following line: complex num1, num2;

5 Examples AddComplex.c

6 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; …… realimg a …… realimg b …… realimg c

7 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; …… realimg a …… realimg b …… realimg c

8 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; 1.02.0 realimg a …… realimg b …… realimg c

9 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; 1.02.0 realimg a …… realimg b …… realimg c

10 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; 1.02.0 realimg a 3.04.0 realimg b …… realimg c

11 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; 1.02.0 realimg a 3.04.0 realimg b …… realimg c

12 AddComplex – step by step complex AddComp(complex x, complex y) { complex z; z.real = x.real + y.real; z.img = x.img + y.img; return z; } 1.02.0 realimg x 3.04.0 realimg y …… realimg z

13 AddComplex – step by step complex AddComp(complex x, complex y) { complex z; z.real = x.real + y.real; z.img = x.img + y.img; return z; } 1.02.0 realimg x 3.04.0 realimg y …6.0 realimg z

14 AddComplex – step by step complex AddComp(complex x, complex y) { complex z; z.real = x.real + y.real; z.img = x.img + y.img; return z; } 1.02.0 realimg x 3.04.0 realimg y 4.06.0 realimg z

15 AddComplex – step by step complex AddComp(complex x, complex y) { complex z; z.real = x.real + y.real; z.img = x.img + y.img; return z; } 1.02.0 realimg x 3.04.0 realimg y 4.06.0 realimg z

16 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; 1.02.0 realimg a 3.04.0 realimg b 4.06.0 realimg c

17 AddComplex – step by step complex a, b, c; printf(…"); scanf("%lf%lf",&(a.real),&(a.img)); printf(…"); scanf("%lf%lf",&(b.real),&(b.img)); c = AddComp(a,b); printf(result = %g+%gi\n",c.real,c.img); return 0; 1.02.0 realimg a 3.04.0 realimg b 4.06.0 realimg c

18 Exercise Implement the MultComplex function – Input - two complex numbers Output – their multiplication Note - If x=a+ib and y=c+id then: z = xy = (ac-bd)+i(ad+bc) Write a program that uses the above function to multiply two complex numbers given by the user

19 Solution MultiplyComplex.c

20 Miscellaneous structure trivia Structure members may be ordinary variable types, but also other structures and even arrays! Structures can therefore be rather large and take up a lot of space Many times we prefer to pass structures to functions by address, and not by value Thus a new copy of the structure is not created – just a pointer to the existing structure

21 More trivia Structures cannot be compared using the == operator They must be compared member by member Usually this will be done in a separate function Structures can be copied using the = operator Member-wise copy

22 Example Is_In_Circle.c

23 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); …… yx d (dot)c (circle) …… yx center (dot) radius …

24 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); …… yx d (dot)c (circle) …… yx center (dot) radius …

25 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) …… yx center (dot) radius …

26 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) …… yx center (dot) radius …

27 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) 0.0 yx center (dot) radius …

28 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) 0.0 yx center (dot) radius …

29 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) 0.0 yx center (dot) radius 5

30 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) 0.0 yx center (dot) radius 5

31 Is_in_circle – step by step int IsInCircle(dot *p_dot, circle *p_circle) { double x_dist,y_dist; x_dist = p_dot->x - p_circle->center.x; y_dist = p_dot->y - p_circle->center.y; if (x_dist*x_dist + y_dist*y_dist radius*p_circle->radius) return 1; return 0; } 1.02.0 yx (dot)(circle) 0.0 yx center (dot) radius 5 x_disty_dist …… p_circlep_dot 1024756

32 Is_in_circle – step by step int IsInCircle(dot *p_dot, circle *p_circle) { double x_dist,y_dist; x_dist = p_dot->x - p_circle->center.x; y_dist = p_dot->y - p_circle->center.y; if (x_dist*x_dist + y_dist*y_dist radius*p_circle->radius) return 1; return 0; } 1.02.0 yx (dot)(circle) 0.0 yx center (dot) radius 5 x_disty_dist 1.0… p_circlep_dot 1024756

33 Is_in_circle – step by step int IsInCircle(dot *p_dot, circle *p_circle) { double x_dist,y_dist; x_dist = p_dot->x - p_circle->center.x; y_dist = p_dot->y - p_circle->center.y; if (x_dist*x_dist + y_dist*y_dist radius*p_circle->radius) return 1; return 0; } 1.02.0 yx (dot)(circle) 0.0 yx center (dot) radius 5 x_disty_dist 1.02.0 p_circlep_dot 1024756

34 Is_in_circle – step by step int IsInCircle(dot *p_dot, circle *p_circle) { double x_dist,y_dist; x_dist = p_dot->x - p_circle->center.x; y_dist = p_dot->y - p_circle->center.y; if (x_dist*x_dist + y_dist*y_dist radius*p_circle->radius) return 1; return 0; } 1.02.0 yx (dot)(circle) 0.0 yx center (dot) radius 5 x_disty_dist 1.02.0 p_circlep_dot 1024756

35 Is_in_circle – step by step int IsInCircle(dot *p_dot, circle *p_circle) { double x_dist,y_dist; x_dist = p_dot->x - p_circle->center.x; y_dist = p_dot->y - p_circle->center.y; if (x_dist*x_dist + y_dist*y_dist radius*p_circle->radius) return 1; return 0; } 1.02.0 yx (dot)(circle) 0.0 yx center (dot) radius 5 x_disty_dist 1.02.0 p_circlep_dot 1024756

36 Is_in_circle – step by step printf(Enter dot\n"); scanf("%lf%lf",&d.x,&d.y); printf("Enter circle center\n"); scanf("%lf%lf",&c.center.x,&c.center.y); printf("Enter circle radius\n"); scanf("%lf",&c.radius); if (IsInCircle(&d, &c)) printf("dot is in circle\n"); else printf("dot is out of circle\n"); 1.02.0 yx d (dot)c (circle) 0.0 yx center (dot) radius 5

37 Exercise Write a struct that represents a date (day, month, year) Write a function that increments the date void IncDate(Date *d); For example – 31.12.05 -> 1.1.06

38 Solution IncDate.c

39 Exiting the program void exit(int status); Sometimes an error occurs and we want the program to immediately exit The exit function closes all open files, frees all allocated memory, and exits the program Equivalent to calling return within main Remember to #include See strcpy_with_exit.c

40 Structures containing arrays A structure member that is an array does not behave like an ordinary array When copying a structure that contains a member which is an array, the array is copied element by element Not just the address gets copied For example - array_member.c Reminder – ordinary arrays cant be copied simply by using the = operator They must be copied using a loop

41 Structures containing arrays The same happens when passing the structure to a function Changing the array inside the function wont change it in the calling function Reminder – when passing an ordinary array to a function, all that gets passed is the address of its first element Hence every change to the array within the function, changes the array in the calling function

42 Pointers are another matter If the member is a pointer, for example to a dynamically allocated array, all that gets copied is the pointer (the address) itself For example, pointer_member.c Hence, we should take extra care when manipulating structures that contain pointers

Download ppt "Structures Often we want to be able to manipulate logical entities as a whole For example, complex numbers, dates, student records, etc Each of these must."

Similar presentations

Introduction to C Programming

Introduction to C Programming
Question Bank. Explain the syntax of if else statement? Define Union Define global and local variables with example Concept of recursion with example.

Question Bank. Explain the syntax of if else statement? Define Union Define global and local variables with example Concept of recursion with example.
Programming in C Chapter 10 Structures and Unions

Programming in C Chapter 10 Structures and Unions
1 Structures. 2 Structure Basics A structure is a collection of data values, called data members, that form a single unit. Unlike arrays, the data members.

1 Structures. 2 Structure Basics A structure is a collection of data values, called data members, that form a single unit. Unlike arrays, the data members.
C How to Program, 6/e ©1992-2010 by Pearson Education, Inc. All Rights Reserved.

C How to Program, 6/e © by Pearson Education, Inc. All Rights Reserved.
C Language.

C Language.
Call By Address Parameters (Pointers) Chapter 5. Functions that “return” more than a single value What if we need more than one value to be returned from.

Call By Address Parameters (Pointers) Chapter 5. Functions that “return” more than a single value What if we need more than one value to be returned from.
C Structures and Memory Allocation There is no class in C, but we may still want non- homogenous structures –So, we use the struct construct struct for.

C Structures and Memory Allocation There is no class in C, but we may still want non- homogenous structures –So, we use the struct construct struct for.
David Notkin Autumn 2009 CSE303 Lecture 13 This space for rent.

David Notkin Autumn 2009 CSE303 Lecture 13 This space for rent.
Programming and Data Structure

Programming and Data Structure
C Structures Basics of structures Typedef. Data Hierarchy Byte –8 bits (ASCII character ‘A’ = 01000001) Field –Group of characters (character string “Fred”)

C Structures Basics of structures Typedef. Data Hierarchy Byte –8 bits (ASCII character ‘A’ = ) Field –Group of characters (character string “Fred”)
F UNCTION O VERLOADING Chapter 5 Department of CSE, BUET 1.

F UNCTION O VERLOADING Chapter 5 Department of CSE, BUET 1.
Structures Spring 2013Programming and Data Structure1.

Structures Spring 2013Programming and Data Structure1.
Single Variable and a Lot of Variables The declaration int k; float f; reserve one single integer variable called k and one single floating point variable.

Single Variable and a Lot of Variables The declaration int k; float f; reserve one single integer variable called k and one single floating point variable.
Structures in C.

Structures in C.
What is a pointer? First of all, it is a variable, just like other variables you studied So it has type, storage etc. Difference: it can only store the.

What is a pointer? First of all, it is a variable, just like other variables you studied So it has type, storage etc. Difference: it can only store the.
Growing Arrays in C By: Victoria Tielebein CS 265- Spring 2011.

Growing Arrays in C By: Victoria Tielebein CS 265- Spring 2011.
Kernighan/Ritchie: Kelley/Pohl:

Kernighan/Ritchie: Kelley/Pohl:
Structures. An array allows us to store a collection of variables However, the variables must be of the same type to be stored in an array E.g. if we.

Structures. An array allows us to store a collection of variables However, the variables must be of the same type to be stored in an array E.g. if we.
Enumerated Types 4 Besides the built-in types, ANSI C allows the definition of user-defined enumerated types –To define a user-define type, you must give.

Enumerated Types 4 Besides the built-in types, ANSI C allows the definition of user-defined enumerated types –To define a user-define type, you must give.

Similar presentations

Ads by Google