Variables

Relax. We'll talk through this in plain words — no textbook voice.

A variable is like a little box that holds data. In C, you have to declare a data type before you can use a variable — because the compiler needs to know how much memory to reserve and how to read the value.

#include <stdio.h>

int main() {
  int age = 20;
  float price = 19.99;
  char grade = 'A';

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

int holds an integer, float holds a decimal number, and char holds a single character. %d, %.2f, and %c are format specifiers — they tell printf how to format the variable in the output.

You should see

Age: 20 Price: 19.99 Grade: A

Info

%.2f means "show exactly 2 decimal places." It's handy when displaying money or prices.

Easy traps

Writing char grade = "A"; with double quotes is wrong — that makes it a string. Use single quotes for a single character.