C Program to Convert Decimal Number to Hexadecimal Number

• Write a C program to convert decimal number to hexadecimal number system.
• How to convert decimal number to hexadecimal number.

Required Knowledge

• C printf and scanf functions
• While loop in C
• Arrays in C

Decimal number system is a base 10 number system using digits 0 and 9 whereas Hexadecimal number system is base 16 number system and using digits from 0 to 9 and A to F. Given an decimal number as input from user convert it to hexadecimal number.

For Example

1234 in Decimal is equivalent to 4D2 in Hexadecimal number system.

C program to convert a decimal number to hexadecimal number

#include <stdio.h> 
#include <string.h> 
   
#define BASE_16 16
 
int main() { 
    char hexDigits[] = "0123456789ABCDEF";
   
    long decimalNumber; 
    char hexadecimalNumber[40]; 
    int index, remaindar; 
       
    /*
     * Take a Decimal Number as input form user
     */ 
    printf("Enter a Decimal Number\n"); 
    scanf("%ld", &decimalNumber);  
   
    index = 0;
      
    /* Convert Decimal Number to Hexadecimal Numbers */ 
    while(decimalNumber != 0) { 
        remaindar = decimalNumber % BASE_16; 
        hexadecimalNumber[index] = hexDigits[remaindar]; 
        decimalNumber /= BASE_16; 
        index++; 
    } 
    hexadecimalNumber[index] = '\0'; 
   
    strrev(hexadecimalNumber); 
   
    printf("Hexadecimal Number : %s", hexadecimalNumber); 
   
    return 0; 
}

Output

Enter a Decimal Number
1234
Hexadecimal Number : 4D2

Enter a Decimal Number
1000
Hexadecimal Number : 3E8