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C program to convert a hexadecimal number into a binary number

Here, we are going to learn how to convert a hexadecimal number into a binary number in C programming language?
Submitted by Nidhi, on July 03, 2021

Problem statement

Here, we will read a hexadecimal number and convert it into a binary number and print the result on the console screen.

C program to convert a hexadecimal number into a binary number

The source code to convert a hexadecimal number into a binary number is given below. The given program is compiled and executed using GCC compile on UBUNTU 18.04 OS successfully.

// C program to convert a hexadecimal number
// into binary number

#include <stdio.h>

int main()
{
    char HexNum[32] = { 0 };
    int i = 0;

    printf("Enter the Hexadecimal number: ");
    scanf("%s", HexNum);

    printf("Binary Number: ");

    while (HexNum[i]) {
        switch (HexNum[i]) {
        case '0':
            printf("0000");
            break;

        case '1':
            printf("0001");
            break;

        case '2':
            printf("0010");
            break;

        case '3':
            printf("0011");
            break;

        case '4':
            printf("0100");
            break;

        case '5':
            printf("0101");
            break;

        case '6':
            printf("0110");
            break;

        case '7':
            printf("0111");
            break;

        case '8':
            printf("1000");
            break;

        case '9':
            printf("1001");
            break;

        case 'a':
        case 'A':
            printf("1010");
            break;

        case 'b':
        case 'B':
            printf("1011");
            break;

        case 'c':
        case 'C':
            printf("1100");
            break;

        case 'd':
        case 'D':
            printf("1101");
            break;

        case 'e':
        case 'E':
            printf("1110");
            break;

        case 'f':
        case 'F':
            printf("1111");
            break;

        default:
            printf("\nInvalid hexa digit: %c", HexNum[i]);
            return 0;
        }
        i++;
    }
    return 0;
}

Output

Enter the Hexadecimal number: A123
Binary Number: 1010000100100011

Explanation

Here, we created a character array HexNum and integer variable i. Then we read the hexadecimal number and convert the number into a binary number and printed the result on the console screen.

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