Convert String to Integer

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

int custom_atoi(const char *str) {

    int num=0;
    int isneg=1;
    
    if(*str == '-') {
        isneg = -1;
        str++;
    } 
    if(*str == '+') {
        str++;
    }

    while(*str != '\0'){

        if(*str >= '0' && *str <= '9') {
           num = num*10 + (*str - '0');      
        } else {
           break;
        }

        str++;
    }

    return num*isneg;
}

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;
}