C Programming Code Examples C > For Loops and While Loops Code Examples program to convert Hexadecimal to Binary number system program to convert Hexadecimal to Binary number system Write a C program to input hexadecimal number from user and convert to binary number system. How to convert hexadecimal number system to binary number system in C program. Hexadecimal number system Hexadecimal number system is a base 16 number system. It uses 16 symbols to represent all numbers i.e. 0123456789ABCDEF Binary number system Binary number system is a base 2 number system. It uses 2 symbols to represent all numbers i.e. 0 and 1. Hexadecimal to binary conversion is divided in three steps. Extract each hex digits separately. Find the binary of each extracted hex digit. Store the binary equivalent of extracted hexadecimal number to final bin variable. Repeat the above three steps till all hexadecimal digits are processed. Hexadecimal to binary 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() { char hex[17], bin[65] = ""; int j = 0; /* Input hexadecimal number from user */ printf("Enter any hexadecimal number: "); gets(hex); /* Extract first digit and find binary of each hex digit */ for(j=0; hex[j]!='\0'; j++) { switch(hex[j]) { case '0': strcat(bin, "0000"); break; case '1': strcat(bin, "0001"); break; case '2': strcat(bin, "0010"); break; case '3': strcat(bin, "0011"); break; case '4': strcat(bin, "0100"); break; case '5': strcat(bin, "0101"); break; case '6': strcat(bin, "0110"); break; case '7': strcat(bin, "0111"); break; case '8': strcat(bin, "1000"); break; case '9': strcat(bin, "1001"); break; case 'a': case 'A': strcat(bin, "1010"); break; case 'b': case 'B': strcat(bin, "1011"); break; case 'c': case 'C': strcat(bin, "1100"); break; case 'd': case 'D': strcat(bin, "1101"); break; case 'e': case 'E': strcat(bin, "1110"); break; case 'f': case 'F': strcat(bin, "1111"); break; default: printf("Invalid hexadecimal input."); } } printf("Hexademial number = %s\n", hex); printf("Binary number = %s", bin); return 0; }