Convert String to Integer

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

int custom_atoi(const char *str) {
    int sign = 1, ret=0;
    if(*str == '-'){
        sign = -1 ;
        *str++;
    }
    if(*str == '+'){
        sign = 1 ;
        *str++;
    }
    while(*str>= '0' && *str<='9'){
        ret *= 10;
        ret += *str - '0';
        *str++;
    }

    return ret*sign;
}

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    printf("%d", custom_atoi(str));
    return 0;
}