Convert String to Integer

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

int is_digit(char c){
    return (c >= '0' && c <= '9');
}

int custom_atoi(const char *str) {
    // Your logic here
    int i = 0;
    int16_t result =0;
    while(str[i] != '\0'){
        if(is_digit(str[i])){
            result = (result * 10) + (str[i] - '0');
        }
        else if(str[0] == '-'){
            result *= -1;
        }
        else if(str[i] == '+' && i == 0){
            // Do nothing
        }
        else{
            break; 
        }
        i++;
    }
    return result;
}

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;
}