Convert String to Integer

Code

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

int custom_atoi(const char *str) {
    int res = 0; 
    int idx = 0; 
    int sign = 1; 
    if (str[0] == '-')
    {
        sign = -1; 
        idx++; 
    }
    else if (str[0] == '+')
    {
        idx++; 
    }

    while (str[idx] != '\0' && (str[idx] >= '0' && str[idx] <= '9'))
    {
        res = (res * 10) + (str[idx] - '0'); 
        idx++;
    }

    return res * 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;
}

Solving Approach