# C++ Program to Convert Decimal Number to HexaDecimal Number

Here is a C++ program to convert hexadecimal to decimal number. In this C++ programs we will learn about fundamentals of decimal and hexadecimal number system, how to convert decimal numbers to hexadecimal numbers and vice-versa. Given a decimal number we have to convert it to hexadecimal number.

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.
For Example:
2016 in Decimal is equivalent to 7E0 in Hexadecimal number system.

## C++ program to convert decimal number to hexadecimal number

```#include <iostream>
#include <cstring>
using namespace std;

#define BASE_16 16

int main() {
char hexDigits[] = "0123456789ABCDEF";

long decimal;
int index, remaindar;

// Take a Decimal Number as input form user
cout << "Enter a Decimal Number\n";
cin >> decimal;

index = 0;

// Convert Decimal Number to Hexadecimal Numbers
while(decimal != 0) {
remaindar = decimal % BASE_16;
decimal /= BASE_16;
index++;
}

cout << "Hexadecimal Number : " << hexadecimal;

return 0;
}
```
Output
```Enter a Decimal Number
753
Hexadecimal Number : 2F1
```
```Enter a Decimal Number
101
Hexadecimal Number : 3F2
```

In above program, we first declare a string hexDigits containing all digits of hexadecimal number system(0-9 and A-F). As hexadecimal numbers contains alphabets as digits, we have to use a character array to store hexadecimal numbers.

## C++ program to convert hexadecimal number to decimal number

```#include <iostream>
#include <cstring>
#include <cmath>
using namespace std;

int main() {
long long decimalNumber=0;
char hexDigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8',
'9', 'A', 'B', 'C', 'D', 'E', 'F'};
int i, j, power=0, digit;

cout << "Enter a Hexadecimal Number\n";

// Converting hexadecimal number to decimal number
for(i=strlen(hexadecimal)-1; i >= 0; i--) {
// search currect character in hexDigits array
for(j=0; j<16; j++){
decimalNumber += j*pow(16, power);
}
}
power++;
}

cout <<"Decimal Number : " << decimalNumber;

return 0;
}
```
Output
```Enter a Hexadecimal Number
2F1
Decimal Number : 753
```

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