Basic Integer Input Validation Without SplashKit

This brief guide provides code to compare how to implement basic input validation for integers with and without SplashKit.
Written by: Simon Rhook and Olivia McKeon
Last updated: December 2024

---

Getting Started without SplashKit

Compiling Your Code

With C++ programs, you will need to adjust the compiling command to link to the libraries being used. Below you will see the different commands to compile with and without SplashKit.

Now, assuming the code filename is program.cpp.

With SplashKit

As usual, you will compile the SplashKit C++ code using the following command:

g++ program.cpp -o test -l SplashKit

Without SplashKit

You can use this command to compile the code below:

g++ program.cpp -o test

Run Your Program

To run the compiled program using one of the commands above, you would use ./test (or ./test.exe if using MSYS2/MINGW64).

Example Code

The following code compares basic input validation for integers with and without SplashKit.

With SplashKit

#include <splashkit.h>

int read_integer(string prompt)
{
    // This function converts user input into an integer with input validation using SplashKit functions.

    string input_string;

    // Prompt user with message in terminal and read input from user
    write(prompt);
    input_string = read_line();

    // Holds program in a loop if user enters a valid integer
    while (!is_integer(input_string))
    {
        write_line("Please enter a valid integer.");
        write(prompt);
        input_string = read_line();
    }

    // Convert to integer and return
    return convert_to_integer(input_string);
}

int main(int argc, char *argv[])
{
    int first_num = read_integer("Please enter first number (whole number): ");
    int second_num = read_integer("Please enter second number (whole number): ");

    write("The sum of the two integers is: ");
    write_line(first_num + second_num);
    return 0;
}

Without SplashKit

#include <iostream>

using namespace std;

string trim(const string &text)
{
    // Function to check trim whitespace from string
    // This is what SplashKit abstracts from the user when calling trim

    size_t first = text.find_first_not_of(' ');
    if (string::npos == first)
    {
        return text;
    }
    size_t last = text.find_last_not_of(' ');
    return text.substr(first, (last - first + 1));
}

bool is_integer(string text)
{
    // Function to check if input is a valid integer
    // This is what SplashKit abstracts from the user when calling is_integer

    string s = trim(text);
    if (s.empty() || ((!isdigit(s[0])) && (s[0] != '-') && (s[0] != '+')))
        return false;

    char *p;
    strtol(s.c_str(), &p, 10);

    return (*p == 0);
}

int read_integer(string prompt)
{
    // This function converts user input into an integer with input validation using non-SplashKit functions.

    string input_string;

    // Prompt user with message in terminal and read input from user
    cout << prompt;
    cin >> input_string;

    // Holds program in a loop if user enters a valid integer
    while (!is_integer(input_string))
    {
        cout << "Please enter a valid integer." << endl;
        cout << prompt;
        cin >> input_string;
    }

    // Convert to integer and return
    return stoi(input_string);
}

int main(int argc, char *argv[])
{
    int first_num = read_integer("Please enter first number (whole number): ");
    int second_num = read_integer("Please enter second number (whole number): ");

    cout << "The sum of the two integers is: ";
    cout << first_num + second_num << endl;

    return 0;
}