C Program to convert hexadecimal to integer

C Program to convert hexadecimal to integer

In this example, we will see a C program through which we can convert hexadecimal bytes into integers.

In this program, first, we will separate both characters that a hexadecimal value contains, and get their integer values and then multiply with 16 and then add second value and we will get the integer value.

/*C program to convert hexadecimal Byte to integer.*/
#include <stdio.h>
//function : getNum
//this function will return number corresponding
//0,1,2..,9,A,B,C,D,E,F
int getNum(char ch)
{
int num=0;
if(ch>='0' && ch<='9')
{
num=ch-0x30;
}
else
{
switch(ch)
{
case 'A': case 'a': num=10; break;
case 'B': case 'b': num=11; break;
case 'C': case 'c': num=12; break;
case 'D': case 'd': num=13; break;
case 'E': case 'e': num=14; break;
case 'F': case 'f': num=15; break;
default: num=0;
}
}
return num;
}
//function : hex2int
//this function will return integer value against
//hexValue - which is in string format
unsigned int hex2int(unsigned char hex[])
{
unsigned int x=0;
x=(getNum(hex[0]))*16+(getNum(hex[1]));
}
int main()
{
unsigned char hexValue[2]="5F";
unsigned int  intValue=0; //can be stored in unsigned char
intValue=hex2int(hexValue);
printf("value is: %d\n",intValue);
return 0;
}