Example: Direct Binary to Hexadecimal Converter in C

// Direct Binary to Hexadecimal Converter
    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h> // For malloc, free

    // Function to get decimal value of a 4-bit binary string
    int getDecimalValue(const char *fourBits) {
        int val = 0;
        if (fourBits[0] == '1') val += 8;
        if (fourBits[1] == '1') val += 4;
        if (fourBits[2] == '1') val += 2;
        if (fourBits[3] == '1') val += 1;
        return val;
    }

    // Function to convert binary string directly to hexadecimal string
    void binaryToHexadecimalDirect(const char *binaryInput, char *hexadecimalOutput) {
        char hexChars[] = "0123456789ABCDEF";
        int len = strlen(binaryInput);
        int outputIndex = 0;
        int padding = 0;

        // Calculate padding needed to make length a multiple of 4
        if (len % 4 != 0) {
            padding = 4 - (len % 4);
        }

        char *paddedBinary = (char *)malloc(len + padding + 1);
        if (paddedBinary == NULL) {
            strcpy(hexadecimalOutput, "ERROR");
            return;
        }

        // Add leading zeros for padding
        for (int i = 0; i < padding; i++) {
            paddedBinary[i] = '0';
        }
        strcpy(paddedBinary + padding, binaryInput); // Copy original binary after padding
        paddedBinary[len + padding] = '\0';

        // Process in 4-bit chunks
        for (int i = 0; i < len + padding; i += 4) {
            char fourBits[5];
            strncpy(fourBits, paddedBinary + i, 4);
            fourBits[4] = '\0'; // Null-terminate the 4-bit string

            int decimalVal = getDecimalValue(fourBits);
            hexadecimalOutput[outputIndex++] = hexChars[decimalVal];
        }
        hexadecimalOutput[outputIndex] = '\0'; // Null-terminate the final hex string

        free(paddedBinary); // Free dynamically allocated memory
    }

    int main() {
        char binaryInput[100];
        char hexadecimalOutput[100];

        printf("Enter a binary number: ");
        scanf("%s", binaryInput);

        binaryToHexadecimalDirect(binaryInput, hexadecimalOutput);

        printf("Binary: %s\n", binaryInput);
        printf("Hexadecimal: %s\n", hexadecimalOutput);

        return 0;
    }