C program to convert Binary to Hexadecimal number system

Write a C program to input binary number from user and convert to hexadecimal number system. How to convert from binary to hexadecimal number system in C. Logic to convert binary to hexadecimal number system in C program.

Enter binary number: 11000010

Hexadecimal: C2

Required knowledge

Basic C programming, For loop

Must have programming knowledge for this program.

Binary number system

Binary number system is a base 2 number system. Binary number system uses only two symbols to represent all its values i.e. 0 and 1

Hexadecimal number system

Hexadecimal number system is base 16 number system. Hexadecimal number system uses 16 symbols to represent all its values i.e. 0123456789ABCDEF

Logic to convert binary to hexadecimal

Binary to hexadecimal conversion algorithm is divided in two parts.

1. Group all binary bits to 4 digits starting from right side.
2. Write corresponding hexadecimal value of each grouped digit.

Binary to hexadecimal conversion table

Decimal	Binary	Hexadecimal
0	0000	0
1	0001	1
2	0010	2
3	0011	3
4	0100	4
5	0101	5
6	0110	6
7	0111	7
8	1000	8
9	1001	9
10	1010	A
11	1011	B
12	1100	C
13	1101	D
14	1110	E
15	1111	F

Program to convert binary to hexadecimal

/**
 * C program to convert binary to hexadecimal number system
 */

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

int main()
{
    int hexConstant[] = {0, 1, 10, 11, 100, 101, 110, 111, 1000, 1001, 1010, 1011, 1100, 1101, 1110, 1111};
    long long binary, tempBinary;
    char hex[20];
    int index, i, digit;
    
    /*
     * Read binary number from user
     */
    printf("Enter binary number: ");
    scanf("%lld", &binary);
    
    /* Copy binary number to temp variable */
    tempBinary = binary;
    index = 0;
    
    /* 
     * Find the hexadecimal of binary number
     */
    while(tempBinary!=0)
    {
        // Group binary to last four digits
        digit = tempBinary % 10000;

        // Find hexadecimal equivalent of last four digit
        for(i=0; i<16; i++)
        {
            if(hexConstant[i] == digit)
            {
                if(i<10)
                {
                    /* 0-9 integer constant */
                    hex[index] = (char)(i + 48);
                }
                else
                {
                    /* A-F character constant */
                    hex[index] = (char)((i-10) + 65);
                }

                index++;
                break;
            }
        }

        // Remove the last 4 digits as it is processed
        tempBinary /= 10000;
    }
    hex[index] = '\0';

    /*
     * Reverse the hex digits
     */
    strrev(hex);

    printf("Binary number = %lld\n", binary);
    printf("Hexadecimal number = %s", hex);

    return 0;
} 

Enter binary number: 01101110
Binary number = 1101110
Hexadecimal number = 6E

Happy coding ;)