## C program to convert decimal to hexadecimal value:

In this post, we will learn how to convert *decimal to hexadecimal* value with an example. Our program will take one number as input from the user and prints out its *hexadecimal* representation.

*Decimal* is a base 10 number system and *hexadecimal* is a base *16* number system.

*Decimal* number system consists of *ten* digits *0, 1, 2, 3, 4, 5, 6, 7, 8, 9* and any number can be represented by these digits. This is the most commonly used number system.
Again, *hexadecimal* number system consists of *16* digits *0* to *9* and *A* to *F*. *10* in decimal is represented by *A* and *15* is represented by *F*.

### How to convert decimal to hexadecimal:

To convert one *decimal* number to *hexadecimal*, we need to keep dividing it by *16* and pick the *remainder*.

For example, Let’s try to convert *1000* to hexadecimal:

- Divide
*1000*by*16*,*1000/16 = 62*, remainder -*8* *62/16 = 3*, remainder -*14**3/16 = 0*, remadinder -*3*

We get the remainders, *3, 14 and 8*. *hexadecimal* value of *14* is *E*. So, hexadecimal value of *1000* is *3E8*

### Decimal to hexadecimal in C algorithm:

So, we need to keep dividing a number by *16* to convert it from *decimal* to *hexadecimal*. But in C, we will have to store the result in an *character array* because the result can be a number or character.

We need to store the integer value as character in the array and this is only possible if we store the *ASCII* value. *ASCII* value of *0* is *48* and *A* is *65*. So, if the remainder is less than *10*, we can add it with *48* and store it in the character array and if it is more than *9*, we will add *55* to it. For example, if it is *10*, we will add *55* and it will become *65*, which is *ASCII* of *A*.

### C program:

Below is the complete C program:

```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
void getHexadecimalValue(int intValue, char *hexa)
{
int rem, i = 0;
while (intValue != 0)
{
rem = intValue % 16;
intValue = intValue / 16;
if (rem < 10)
{
hexa[i++] = 48 + rem;
}
else
{
hexa[i++] = 55 + rem;
}
}
hexa[i] = '\0';
}
int main()
{
int givenNum;
char *hexaValue;
hexaValue = malloc(sizeof(char) * 50);
printf("Enter a number : ");
scanf("%d", &givenNum);
getHexadecimalValue(givenNum, hexaValue);
int strLength = strlen(hexaValue);
for (int j = strLength - 1; j >= 0; j--)
{
printf("%c", hexaValue[j]);
}
printf("\n");
}
```

### Explanation:

- Here,
*getHexadecimalValue*method is used to convert one integer value to*hexadecimal*. - It takes two parameters,
*intValue*is the given integer value and one*char**to put the*hexadecimal*converted result. - Inside
*main()*, we are calling*getHexadecimalValue*with a user input number*givenNum*and a*char***hexaValue*to store the result. The result is copied to*hexaValue*but it is in reverse order. - To print the actual hexadecimal converted value, we are using one
*for loop*to iterate the*char**in reverse order and printing the characters one by one.

### Sample Output:

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