Convert String to Integer

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

int custom_atoi(const char *str) {
    int val = 0;
    char first_char;
    while(*str == ' ' || *str == '\n'){
        str++;
    }       //remove leading whitespaces 
    first_char = *str;      //assign sign if present
    if(first_char == '+' || first_char == '-'){
        str++;
    }
    while( (*str >= '0') && (*str <= '9') ){
        val = (val*10) + (*str - '0');
        str++;
    }
    return (first_char == '-') ? -val : val; //convert to negative 
}

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;
}