Convert a string from UART to hex value in c - microcontroller

Question

I am working on pic controllers. I have a string "040F" which is sent to the controller through UART.
I want to convert this string to a hex representation such as 0x040F. I tried a code snippet but no success.
Can anyone please help me out.

Answer 1

If what you mean is to convert a hex string to binary, the below code can help. It may not be an optimized one and may be other simpler solutions are available in the internet and can be even buggy. But it will give you some idea, I hope.
#include<stdio.h>
#include<string.h>
#define MAX_STR_LEN 16
int hex_char_to_bin(char ch)
{
if(ch >= '0' && ch <= '9')
{
return (ch - '0');
}
else if(ch >= 'a' && ch <= 'f')
{
return (10 + ch - 'a');
}
else if(ch >= 'A' && ch <= 'F')
{
return (10 + ch - 'A');
}
return -1;
}
int hex_str_to_bin(const char *hex_str, int *result)
{
int str_len, i;
int bin_val = 0;
str_len = strnlen(hex_str, MAX_STR_LEN);
for (i = 0; i < str_len; i++)
{
int val = hex_char_to_bin(*hex_str++);
if (val == -1)
return -1;
bin_val = (bin_val<<4) + val;
}
*result = bin_val;
return 0;
}
int main()
{
char str[] = "043f";
int hex;
if(!hex_str_to_bin(str, &hex))
printf("%x\n",hex);
else
printf("Invalid hex charecters in string\n");
return 0;
}