Convert a hexadecimal string to an integer efficiently in C?

Question

In C, what is the most efficient way to convert a string of hex digits into a binary unsigned int or unsigned long?

For example, if I have

Answer 1

In C you can convert a hexadecimal number to decimal in many ways. One way is to cast the hexadecimal number to an integer. I personally found this to be simple and small.

Here is an sample code for converting a Hexadecimal number to a Decimal number with the help of casting.

#include 

int main(){
    unsigned char Hexadecimal = 0x6D;   //example hex number
    int Decimal = 0;    //decimal number initialized to 0


        Decimal = (int) Hexadecimal;  //conversion

    printf("The decimal number is %d\n", Decimal);  //output
    return 0;
}