How to convert binary to Hex by using C language?

Binary numbers are represented using only 1's and 0's. Hexadecimal numbers use 16 digits: {0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F} where A=10, B=11, C=12, D=13, E=14, F=15.

Syntax

// Convert binary string to decimal first, then to hex
int binaryToDecimal(long binary);
void decimalToHex(int decimal, char hex[]);

Converting Binary to Hex Process

To convert binary to hexadecimal, group the binary digits into 4-bit blocks (nibbles) from right to left. Each 4-bit group represents one hexadecimal digit −

Method 1: Using String Input

This approach takes binary as a string and converts it directly to hexadecimal −

#include <stdio.h>
#include <string.h>
#include <math.h>

int binaryToDecimal(char binary[]) {
    int decimal = 0;
    int base = 1;
    int len = strlen(binary);
    
    for (int i = len - 1; i >= 0; i--) {
        if (binary[i] == '1') {
            decimal += base;
        }
        base *= 2;
    }
    return decimal;
}

int main() {
    char binary[32];
    printf("Enter binary number: ");
    scanf("%s", binary);
    
    int decimal = binaryToDecimal(binary);
    printf("Binary: %s<br>", binary);
    printf("Decimal: %d<br>", decimal);
    printf("Hexadecimal: %X<br>", decimal);
    
    return 0;
}

Enter binary number: 11100101
Binary: 11100101
Decimal: 229
Hexadecimal: E5

Method 2: Using Integer Input

This method takes binary as an integer and converts it step by step −

#include <stdio.h>

int main() {
    long int binaryval, decimal = 0, base = 1, remainder;
    
    printf("Enter the binary number: ");
    scanf("%ld", &binaryval);
    
    long int temp = binaryval;
    
    // Convert binary to decimal
    while (binaryval != 0) {
        remainder = binaryval % 10;
        decimal = decimal + remainder * base;
        base = base * 2;
        binaryval = binaryval / 10;
    }
    
    printf("Binary: %ld<br>", temp);
    printf("Decimal: %ld<br>", decimal);
    printf("Hexadecimal: %lX<br>", decimal);
    
    return 0;
}

Enter the binary number: 11100
Binary: 11100
Decimal: 28
Hexadecimal: 1C

Comparison Table

Key Points

• Each group of 4 binary digits equals one hexadecimal digit
• Conversion process: Binary ? Decimal ? Hexadecimal
• Use %X format specifier for uppercase hex output
• Use %x format specifier for lowercase hex output

Conclusion

Converting binary to hexadecimal in C involves first converting to decimal, then using printf with %X format. Both string and integer methods work effectively depending on your input requirements.