Variables and Data Types

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Last Updated on: 23rd Jan 2025 11:24:04 AM

1. What is a Variable?

In simple terms, a variable is a named storage location in the computer's memory that holds a value. Think of it as a container that can hold different types of data.

• Name (Identifier): Every variable has a name that uniquely identifies it. This name is used to access the variable's value.
• Type: A variable has a type that determines the kind of data it can store (e.g., integer, floating-point number, character).
• Value: The actual data stored in the variable. This value can change during the program's execution (hence the name "variable").

2. Declaring Variables

Before using a variable in C, you must declare it. Declaration tells the compiler the variable's name and its data type. The general syntax is:

data_type variable_name;

Examples:

int age;         // Declares an integer variable named age
float price;       // Declares a floating-point variable named price
char initial;      // Declares a character variable named initial

You can also declare and initialize a variable in the same line:

int score = 100;   // Declares an integer variable score and initializes it to 100
float pi = 3.14159; // Declares a float variable pi and initializes it
char grade = 'A';  // Declares a char variable grade and initializes it to 'A'

3.Data Types in C

C provides several built-in data types:

• Primitive Types:

• Integer Types: Used for whole numbers (without decimal points).

  • int: The most common integer type. Typically 4 bytes (but can vary depending on the system).
  • short int (or short): Smaller integer type, usually 2 bytes.
  • long int (or long): Larger integer type, usually 4 or 8 bytes.
  • long long int (or long long): Even larger integer type, usually 8 bytes.
  • unsigned int, unsigned short, unsigned long, unsigned long long: These are the unsigned versions of the above types. They can only store non-negative values (0 and positive numbers), effectively doubling the positive range.
• Derived Types:
  • Arrays, Pointers, Structures, etc.

Example:

#include <stdio.h>

int main() {
    int number = 10;
    char grade = 'A';
    float percentage = 85.5;

    printf("Number: %d\n", number);
    printf("Grade: %c\n", grade);
    printf("Percentage: %.1f\n", percentage);

    return 0;
}

 

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