Convert String to Integer

Code

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

int custom_atoi(const char *str) {
    int sum = 0;
    int i = 0;
    int sign = 0;
    char c;

    if(str[0] == '+')
    {
        sign = 1;
        i = 1;
    }
    else if(str[0] == '-')
    {
        sign = -1;
        i = 1;
    }

    while(str[i])
    {
        c = str[i];
        if(c >= '0' && c <= '9')
        {
            sum = sum * 10 + c - '0';
            i++;
        }
        else
            break;        
    }
    if(sign != 0)
        sum = sum * sign;
        
    return sum;
}

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