Convert Hexadecimal String to Integer Without strtol or sscanf functions

Code

#include <stdio.h>
#include <stdint.h>
uint16_t hexconv(char c)
{
    if(c >= '0' && c <= '9')
        return c - '0';
    
    c |= 0x20;

    if(c >= 'a' && c <= 'f')
        return (c - 'a' + 10);
}
uint16_t hex_to_uint(const char *str) {
    // Your logic here
    uint16_t result = 0;
    int hex = 0;

    for(;*str; ++str)
    {
        hex = hexconv(*str);
        result = (result << 4) | hex;
    }

    return result;
}

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

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

Solving Approach