Convert Hexadecimal String to Integer Without strtol or sscanf functions

Code

#include <stdio.h>
#include <stdint.h>

uint16_t hex_to_uint(const char *str) {
    // Your logic here
    uint16_t res=0;
    uint16_t value =0;
    int i=0;
    while(str[i] != '\0'){
    if (str[i] >= '0' && str[i] <= '9')
            value = str[i] - '0';
        else if (str[i] >= 'A' && str[i] <= 'F')
            value = str[i] - 'A' + 10;
        else if (str[i] >= 'a' && str[i] <= 'f')
            value = str[i] - 'a' + 10;
        
        res = res * 16 + value;
        i++;

    }
    return res;
}

int main() {
    char hex[10];
    scanf("%s", hex);

    printf("%u", hex_to_uint(hex));
    return 0;
}

Solving Approach