Using structs
- C course
- Beginner
- Lesson 95/116
- 4 min
Learn to declare struct variables and access fields.
struct variable and member access
After defining a struct you can create variables. To access members you use the . operator.
struct Point p;
p.x = 5;
p.y = 10;Here p is a struct Point variable. With p.x you reach the x member and can assign a value. You can also initialize with {5, 10} at definition. You can also modify members one by one.
Initialization styles
You can give a struct variable its value at definition or later. Initialization uses curly braces.
struct Point a = {1, 2};
struct Point b;
b.x = 3;
b.y = 4;
struct Point c = a;Here a takes its value at definition; b is declared first then its members are assigned one by one; c becomes a copy of a. All three are valid; you choose one depending on the situation. Member access is always with ..
Practice Assign members and sum
Declare struct Point p. Assign p.x = 5 and p.y = 10. Print the sum p.x + p.y with printf.
Starter code
#include <stdio.h>
struct Point { int x; int y; };
int main(void) {
/* Declare a Point variable; assign x=5, y=10; print the sum with printf */
return 0;
}Sample solution
struct Point p;
p.x = 5;
p.y = 10;
printf("%d\n", p.x + p.y);Expected output
15
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match declaration to meaning
| Term | Meaning |
|---|---|
struct Point p; |
Variable declaration |
p.x = 5; |
Member assignment |
{3, 4} |
Initial value |
p.x |
Member access |
2 Which operator is used to access a struct member?
- ->
- *
- ::
- . Correct answer
Explanation: Member access on a struct variable uses .
3 Fill in the blank: member access
struct Point p;
p____ = 5;struct Point p;
p.x = 5;Explanation: p.x accesses the x member.