Variables

1 min read | C Tutorial

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Variables are how you store data in C. Think of them as labeled boxes. You put a value in a box, give it a name, and later you can look inside that box or change what is in it.

Declaring a Variable

In C, you have to declare a variable before you can use it. Declaration tells the compiler: "Hey, I need a box named age that holds an integer."

The syntax is: type name;


int age;
float price;
char letter;

Naming Rules

C has strict rules for variable names:

Names can contain letters, digits, and underscores
Names must start with a letter or underscore — never a digit
Names are case-sensitive: age and Age are different
No spaces or special characters like @, #, $
You cannot use C keywords like int, return, if as names

Assigning and Printing

You assign a value with =. You print with printf and format specifiers like %d for integers and %f for floats.


#include <stdio.h>

int main() {
  int age = 25;
  float price = 19.99;
  char grade = 'A';

  printf("Age: %d\n", age);
  printf("Price: %.2f\n", price);
  printf("Grade: %c\n", grade);
  return 0;
}