Example: Hexadecimal to Binary Converter using Switch in C

// Hexadecimal to Binary Converter using Switch
#include <stdio.h>
#include <string.h> // Required for strlen()
#include <ctype.h>  // Required for toupper()

// Function to convert a single hexadecimal digit to its 4-bit binary equivalent
void hexToBinary(char hexDigit) {
    switch (toupper(hexDigit)) { // Convert to uppercase for consistent comparison
        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': printf("1010"); break;
        case 'B': printf("1011"); break;
        case 'C': printf("1100"); break;
        case 'D': printf("1101"); break;
        case 'E': printf("1110"); break;
        case 'F': printf("1111"); break;
        default:  printf("\nError: Invalid hexadecimal digit '%c'\n", hexDigit);
    }
}

int main() {
    char hexNum[20]; // Buffer to store hexadecimal input
    int i = 0;

    // Step 1: Prompt user for input
    printf("Enter a hexadecimal number: ");
    scanf("%s", hexNum);

    printf("Binary equivalent: ");

    // Step 2: Iterate through each character of the hexadecimal string
    while (hexNum[i] != '\0') {
        hexToBinary(hexNum[i]); // Call function to convert and print
        i++;
    }
    printf("\n");

    return 0;
}