C Program to Convert Hexadecimal Number to Binary

#include <stdio.h>

// Function to convert hexadecimal to binary
void hexToBinary(char hex[])
{
    printf("Hexadecimal number: %s\n", hex);
    printf("Binary number: ");

    int i = 0;
    while (hex[i]) {
        switch (hex[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 hexadecimal digit %c", hex[i]);
                return;
        }
        i++;
    }
}

int main()
{
    char hex[20];

    printf("Enter a hexadecimal number: ");
    scanf("%s", hex);

    hexToBinary(hex);

    return 0;
}