Convert String to Integer

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

int custom_atoi(const char *str) {
    // Your logic here
    int result = 0;
    int sign = 0;

    // first character is positive
    if (str[0] == '+') {
        for (int i = 1; str[i] != '\0'; i++) {
            if (str[i] >= '0' && str[i] <= '9') {
                result = result * 10 + (str[i] - '0');
            }
            else {
                break;
            }
        }
    }
    // first character is negative
    else if (str[0] == '-') {
        sign = 1;
        for (int i = 1; str[i] != '\0'; i++) {
            if (str[i] >= '0' && str[i] <= '9') {
                result = result * 10 + (str[i] - '0');
            }
            else {
                break;
            }
        }
    }
    else {
        // first character is a number
        for (int i = 0; str[i] != '\0'; i++) {
            if (str[i] >= '0' && str[i] <= '9') {
                result = result * 10 + (str[i] - '0');
            }
            else {
                break;
            }
        }
    }

    if (sign == 0) {
        return result;
    } else {
        return result * -1;
    }
}

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;
}