C Variables
A variable is a named location in memory used to store a value. In C, every variable must be declared with a specific type before it can be used, and that type never changes.
Variable names must start with a letter or underscore, can contain digits, and cannot be a reserved keyword. Choosing clear variable names makes your code much easier to read.
type name = value;Declaring and initializing
A declaration reserves memory of the right size for a type, such as `int age;`. You can also initialize a variable with a value at the same time, like `int age = 25;`.
Naming rules
Names are case-sensitive and can include letters, digits and underscores, but cannot start with a digit. Avoid C keywords like int, return or for as variable names.
#include <stdio.h>
int main() {
int age = 25;
float price = 9.99;
printf("%d %.2f\n", age, price);
return 0;
}25 9.99Two variables of different types are declared, initialized and printed.
#include <stdio.h>
int main() {
int x, y;
x = 5;
y = 10;
printf("Sum: %d\n", x + y);
return 0;
}Sum: 15Multiple variables of the same type can be declared on one line, then assigned separately.
Key points
- Every variable in C has a fixed, declared type.
- Variables can be declared and initialized in one statement.
- Names are case-sensitive and cannot start with a digit.
- Uninitialized local variables hold indeterminate garbage values.