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
    int i =0;
    int num = 0;
    while(str[i] != '\0'){
        num = num * 16;
        if( str[i] >= '0' && str[i] <= '9'){
            num = num + (str[i] - '0');
        }else if (str[i] >= 'A' && str[i] <= 'Z'){
            num = num + ((str[i]) - 'A' + 10);
        }else if (str[i] >= 'a' && str[i] <= 'z'){
            num = num + ((str[i]) - 'a' + 10);
    }
    i++;
  }
  return num;
}

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

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

Solving Approach