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 num = 0;
    int strval=0;
    while(*str != '\0')
    {
        if(*str <= '9' && *str >= '0')
        {
        strval = *str - '0';
        }
        else if(*str >= 'A' && *str <= 'F')
        {
            strval = *str - 'A'+ 10;
        }
        else if (*str >= 'a' && *str <= 'f')
        {
            strval = *str - 'a'+ 10;
        }
        else
        {
            return 0;
        }
        num = (num << 4) |(strval & 0xFF);
        str++;
    }
    return num;
}

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

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

Solving Approach