Data Types in C

In C programming, data types specify how the data is to be stored and manipulated.

The basic C data types are:

int: int is used to store integer values (whole numbers). It typically occupies 4 byte of memory.
float: float is used to store floating-point numbers (numbers with decimal points), typically providing 6 decimal digits of precision. It typically occupies 4 byte of memory.
double: double is used to store floating-point numbers with double precision, typically providing 15 decimal digits of precision. It typically occupies 8 byte of memory.
char: char is used to store single characters (like letters, digits, symbols). It typically occupies 1 byte of memory.
_Bool: _Bool is used for 'True' or 'False' (0 or 1). 0 represents false and non-zero represents true.

Derived data types are:

Arrays: An array is a collection of items of the same data type stored under a single name.
Pointers: Pointers store memory addresses of variables. They are used for advanced memory management.
Structures: Structures allow you to group variables of different data types under a single name, creating user-defined data types.
Unions: Unions are similar to structures, but all members share the same memory location. This is useful when you know only one member will have a value at a time.

Other data types:

void: void indicates the absence of a value. It's often used for functions that don't return any value.

Create Integer Data Type in C

To define an integer data type, use int keyword before variable name.

Examples of Integer Data Type

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#include <stdio.h>
​
    int main() {
        int num; // Declares an integer variable named 'num'
        num = 100; // Assigns the integer value 100 to the variable 'num'
        printf("%d", num);
        return 0;
    }
​

Example explained

int num;: The code declares an integer variable named 'num'.
num = 100;: It assigns the integer value 100 to the variable 'num'.
printf("%d", num);: It prints the value of integer variable named 'num'. '%d' is the format specifier for integer.

Create Float Data Type in C

To define a float data type, use float keyword before variable name.

Examples of Float Data Type

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#include <stdio.h>
​
    int main() {
        float numFloat; // Declares a float variable named 'numFloat'
        numFloat = 32.54; // Assigns the float value 32.54 to the variable 'numFloat'
        printf("%f", numFloat);
        return 0;
    }
​

Example explained

float numFloat;: The code declares a float variable named 'numFloat'.
numFloat = 32.54;: It assigns the float value 32.54 to the variable 'numFloat'.
printf("%f", numFloat);: It prints the value of float variable named 'numFloat'. '%f' is the format specifier for float.

Create Double Data Type in C

To define a double data type, use double keyword before variable name.

Examples of Double Data Type

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#include <stdio.h>
​
    int main() {
        double numDouble; // Declares a double variable named 'numDouble'
        numDouble = 564.25647; // Assigns the double value 564.25647 to the variable 'numDouble'
        printf("%lf", numDouble);
        return 0;
    }
​

Example explained

double numDouble;: The code declares a double variable named 'numDouble'.
numDouble = 564.25647;: It assigns the double value 564.25647 to the variable 'numDouble'.
printf("%lf", numDouble);: It prints the value of double variable named 'numDouble'. '%lf' is the format specifier for double.

Create Char Data Type in C

To define a char data type, use char keyword before variable name.

Examples of Char Data Type

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#include <stdio.h>
​
    int main() {
        char letter; // Declares a char variable named 'letter'
        letter = 'A'; // Assigns the char value 'A' to the variable 'letter'
        printf("%c", letter);
        return 0;
    }
​

Example explained

char letter;: The code declares a char variable named 'letter'.
letter = 'A';: It assigns the char value 'A' to the variable 'letter'.
printf("%c", letter);: It prints the value of char variable named 'letter'. '%c' is the format specifier for char.

Create Boolean Data Type in C

To define a boolean data type, use bool keyword before variable name.

You must include stdbool.h header to use bool.

Examples of Boolean Data Type

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#include <stdio.h>
#include <stdbool.h>
​
    int main() {
        bool isTrue; // Declares a boolean variable
        isTrue = true; // Assigns true value
        printf("isTrue: %s\n", (isTrue) ? "true" : "false");
        return 0;
    }
​

Example explained

bool isTrue;: The code declares a boolean variable named 'isTrue'.
isTrue = true;: It assigns the boolean value 'true' to the variable 'isTrue'.
printf("isTrue: %s\n", (isTrue) ? "true" : "false"): It prints the value of boolean variable named 'isTrue'. The ternary operator method is used for better readability.

Create Array in C

To declare an array, specify the data type of the elements before the array name. The array name must be followed by square brackets []. The size of the array is put in the square brackets in integer value greater than zero.

Array elements are placed between curly braces '{}' and are separated by comma.

You can initialize the array with elements at the time of declaration or you can add elements later.

Examples of Array

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#include <stdio.h>
​
    int main() {
        int numbers[5] = {1, 2, 3, 4, 5}; // Declare and initialize the array
​
        printf("%d\n", numbers[2]);
​
        return 0;
    }
​

Example explained

int numbers[5] = {1, 2, 3, 4, 5};: The code declares and initializes an integer array of 5 numbers.
printf("%d\n", numbers[2]);: It prints the third element of integer array. Index of C array is 0 (zero) based.

Create Pointer in C

Specify the data type of the pointer.
Use the * operator to declare a pointer variable name. The * operator is conventionally placed at the beginning of the variable name to indicate that it's a pointer.
Use the address-of operator '&' before a variable to get the memory address of the variable, and assign it to the pointer variable.

Examples of Pointer

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#include <stdio.h>
​
    int main() {
​
        int num = 20;
        int *numptr = &num; //Declaring pointer and assigning value
        printf("The memory address of num variable: %p\n", numptr); // %p is format specifier for pointer
​
        return 0;
    }
​

Example explained

int num = 20;: The code declares and initializes an integer variable 'num'.
int *numptr = #: It declares a pointer name '*numptr' and assigns the memory address of 'num' variable using '&num'. Please note that '&' operator is used with 'num' varibale to get the memory address of the variable.
printf("The memory address of num: %p\n", numptr);: It prints the memory address of 'num' variable using pointer 'numptr'. '%p' is the format specifier for pointer.

Create Structure in C

Use 'struct' keyward before structure name like struct Person. Person is the user defined name of structure.
Define members of the structure inside curly braces '{}' like { char name[60]; int age; };. Declare data type before the member name to define a struct member.

Please take a closer look at the following example.

Examples of Pointer

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#include <stdio.h>
#include <string.h>
​
​
    // Define a structure named 'Person'
    struct Person {
    char name[60];
    int age;
    };
​
    int main() {
    // Declare a variable of type 'Person' structure
    struct Person person1;
​
    // copy string to name member
    strcpy(person1.name, "John Done");
    person1.age = 35;
    //print person1
    printf( "%s is %d years old.", person1.name, person1.age);
    return 0;
    }
​

Example explained

struct Person { char name[60]; int age;}; : The line declares Person structure with two members - 'name' and 'age'.
struct Person person1;: It declares a variable of type 'Person' structure name 'person1'.
strcpy(person1.name, "John Done");: The line copies string value ("John Done") to the name member.
person1.age = 35;: It assigns '35' to the 'age' member of Person structure.
printf( "%s is %d years old.", person1.name, person1.age);: It prints the member values of Person structure.

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How to create different data types in C

Data Types in C

The basic C data types are:

Derived data types are:

Other data types:

Create Integer Data Type in C

Examples of Integer Data Type

Example explained

Create Float Data Type in C

Examples of Float Data Type

Example explained

Create Double Data Type in C

Examples of Double Data Type

Example explained

Create Char Data Type in C

Examples of Char Data Type

Example explained

Create Boolean Data Type in C

Examples of Boolean Data Type

Example explained

Create Array in C

Examples of Array

Example explained

Create Pointer in C

Examples of Pointer

Example explained

Create Structure in C

Examples of Pointer

Example explained

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