C Programming Code Examples C > For Loops and While Loops Code Examples C program to convert Binary to Hexadecimal number system 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 binary to hexadecimal number system in C 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 Binary to hexadecimal conversion algorithm is divided in two parts. Group all binary bits to 4 digits starting from right side. 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 #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; /* Input binary number from user */ printf("Enter binary number: "); scanf("%lld", &binary); /* Copy binary number to temp variable */ tempBinary = binary; index = 0; /* Find 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; }