# C program to convert Hexadecimal to Decimal

Hexadecimal to Decimal conversion in C:

We can convert any decimal number (base-10 (0 to 9)) into hexadecinal number(base-16 (0 or 9 and A(10),B(11),C(12),D(13),E(14),F(15)) by c program.

Decimal Number

Decimal number is a base 10 number because it ranges from 0 to 9, there are total 10 digits between 0 to 9. Any combination of digits is decimal number such as 23, 445, 132, 0, 2 etc.

Hexadecimal Number

Hexadecimal number is a base 16 number because it ranges from 0 or 9 and A(10),B(11),C(12),D(13),E(14),F(15). Any combination of digits is Hexadecimal number such as A34, 5A4, 7DE7, ABCD etc.

To understand this example, you should have the knowledge of the following C programming topics:

C Functions
C User-defined functions

```/*program to convert number from hexadecimal to decimal*/

#include <stdio.h>
#include <string.h>
#include <math.h>

int main()
{
char hex[32]={0};
int  dec,i;
int  cnt;	/*for power index*/
int  dig;	/*to store digit*/

printf("Enter hex value: ");
gets(hex);

cnt=0;
dec=0;
for(i=(strlen(hex)-1);i>=0;i--)
{
switch(hex[i])
{
case 'A':
dig=10; break;
case 'B':
dig=11; break;
case 'C':
dig=12; break;
case 'D':
dig=13; break;
case 'E':
dig=14; break;
case 'F':
dig=15; break;
default:
dig=hex[i]-0x30;
}
dec= dec+ (dig)*pow((double)16,(double)cnt);
cnt++;
}

printf("DECIMAL value is: %d",dec);
return 0;
}
```

Output:

Enter hex value: A
DECIMAL value is: 10

Enter hex value: A1
DECIMAL value is: 161

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