Data types in C

A data types in C defines the type of data that a variable can hold.

• It determines the size and layout of the variable’s memory, the range of values that can be stored, and the set of operations that can be performed on it.

C has several built-in data types categorized as:

• Basic (Primitive) Data Types
• Derived Data Types
• User-defined Data Types

1.) Basic Data Types:

a.) int (Integer):

• Used to store whole numbers (both positive and negative) without fractional parts.
• Typically occupies 2 or 4 bytes depending on the system.
• Example values: -10, 0, 100

b.) float (Floating-point):

• Used to store single-precision real numbers (numbers with fractional parts).
• Usually occupies 4 bytes.
• Example values: 3.14, -0.001, 2.5e3

c.) double (Double Precision Floating-point):

• Used to store double-precision real numbers (more precise than float).
• Usually occupies 8 bytes.
• Example values: 3.1415926535, 1.0e-10

d.) char (Character):

• Used to store a single character or a small integer.
• Typically occupies 1 byte.
• Example values: ‘A’, ‘z’, ‘0’

Example:

#include <stdio.h>

int main() {
    int age = 30;
    float pi = 3.14159f;
    double e = 2.718281828459045;
    char grade = 'B';

    printf("Age: %d\n", age);
    printf("PI: %.5f\n", pi);
    printf("Euler's Number: %.15lf\n", e);
    printf("Grade: %c\n", grade);

    return 0;
}

2.) Derived Data Types:

a.) Arrays:

• Collection of elements of the same data type stored contiguously.
• Example: int numbers[5]; holds 5 integers.

b.) Pointers:

• Variables that store memory addresses.
• Example: int *ptr;

c.) Structures:

• User-defined collection of variables of different types.
• Example: struct Person { char name[50]; int age; };

Example:

#include <stdio.h>

// Structure definition
struct Person {
    char name[50];
    int age;
};

int main() {
    // Array of integers
    int numbers[5] = {10, 20, 30, 40, 50};

    // Pointer to integer
    int *ptr = &numbers[0];

    // Structure variable
    struct Person person1 = {"John Doe", 28};

    // Print array elements using pointer
    printf("Array elements:\n");
    for (int i = 0; i < 5; i++) {
        printf("%d ", *(ptr + i));
    }
    printf("\n");

    // Print structure members
    printf("Name: %s\n", person1.name);
    printf("Age: %d\n", person1.age);

    return 0;
}

3.) User-defined Data Types:

a.) enum (Enumeration):

• A data type consisting of named integer constants.

Example:

#include <stdio.h>

// Enum declaration
enum Day { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday };

int main() {
    enum Day today = Wednesday;

    // Print enum value (integer)
    printf("Enum value of today: %d\n", today);

    // Use enum in condition
    if (today == Wednesday) {
        printf("Today is Wednesday.\n");
    }

    return 0;
}