Convert String to Integer

Code

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

int custom_atoi(const char *str) {
    int i=0, sign = 1, num = 0;
    if (str[0] == '-') sign=-1;
    while (str[i] != '\0') {
        if ((str[i] >= '0') && (str[i] <= '9')) {
            num = num * 10 + (str[i]-'0');
        } else if ((i==0) && ((str[i] == '+') || (str[i] == '-'))){
            num=num;
        }
        else {
            break;
        }
        i++;
    }
    return sign*num;
}

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