Conversion of Hex decimal to integer value using C language

Problem

How to convert the hexadecimal value to integer value by using the C programming language?

Explain the concept.

Solution

Hexadecimal values represent in 16 symbols 1 to 9 & A to F. Here, A to F decimal equivalent is 10 to 15.

Example

Following is the C program for converting hexadecimal to an integer by using functions −

#include<stdio.h>
#include<string.h>
#include<math.h>
int hextodc(char *hex){
   int y = 0;
   int dec = 0;
   int x, i;
   for(i = strlen(hex) - 1 ; i >= 0 ; --i)//{
      if(hex[i]>='0'&&hex[i]<='9'){
         x = hex[i] - '0';
      }
      else{
         x = hex[i] - 'A' + 10;
      }
      dec = dec + x * pow(16 , y);// converting hexadecimal to integer value ++y;
   }
   return dec;
}
int main(){
   char hex[100];
   printf("Enter Hexadecimal: ");
   scanf("%s", hex);
   printf("\nDecimal: %d", hextodc(hex));
   return 0;
}

Output

When the above program is executed, it produces the following result −

1. Enter Hexadecimal: A
   Decimal: 10
   2. Enter Hexadecimal: A12
      Decimal: 2578

Explanation

Scan all characters of Hex from Right-To-Left

Let scanned character be A.

Convert A to appropriate decimal form and store it in x.

dec = dec + x * 16y

y= y + 1.

Return decimal.

We can also scan the Hexadecimal value from Left-To-Right but, we must initialize y as y = N – 1 and decrement y on each iteration. N is the length of Hexadecimal.