Skip to content

Simple C++ console application that prompts the user to enter their age, validates that the input is a number between 1 and 99; otherwise, it displays an error message and re-prompts until a valid age is entered.

Notifications You must be signed in to change notification settings

mpluxery/Basic-CPP-age-checker

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 

History

7 Commits
 
 
 
 

Repository files navigation

Valid Age Checker in C++

Description

This is a simple C++ program that prompts the user to enter their age and validates that the input is a numeric value between 1 and 99, with no extra characters. If the input does not meet these criteria, the program displays an error message and asks again until a valid age is entered. Once a valid number is provided, it outputs a confirmation message including the entered age.

Installation and Build

  1. Make sure you have a C++ compiler installed (for example, g++).
  2. Save the source code below into a file named io.cpp.
  3. Open a terminal in the same directory as io.cpp and run:

g++ io.cpp -o valid_age

Usage After a successful build, execute the program by typing:

./valid_age When prompted:

Enter Age: type a number between 1 and 99 and press Enter.

If the input is invalid (non-numeric characters, numbers outside 1–99, or extra characters), the program will print:

be for real! and prompt again.

Once a valid age is entered, you will see:

You are years old, seems legit! For example:

You are 25 years old, seems legit! Source Code (io.cpp)

#include #include #include

int main() { int age = 0; bool valid = false; char null = '\0';

while (!valid)
{
    std::cout << "Enter Age: ";

    std::string line;
    std::getline(std::cin, line);

    std::stringstream is(line);

    // Validate:  
    // 1. Attempt to extract an integer into `age`.  
    // 2. Check for any extra characters after the number.  
    // 3. Ensure age is between 1 and 99 (inclusive).
    if (!(is >> age) || (is >> std::ws && is.get(null)) || age >= 100 || age <= 0)
        std::cout << "be for real!" << std::endl;
    else
        valid = true;
}

std::cout << "You are " << age << " years old, seems legit!" << std::endl;
return 0;

} How It Works Variables

age (int): Stores the user’s age.

valid (bool): Becomes true once a valid age is entered.

null (char): Used to detect any extra character after the numeric input.

Input Loop

The while (!valid) loop repeatedly prompts the user to enter their age.

std::getline(std::cin, line) reads the entire line of input as a string.

String Parsing and Validation

A std::stringstream named is is initialized with the input line.

is >> age attempts to parse an integer; if this fails, the input is not a valid number.

(is >> std::ws && is.get(null)) checks for any non-whitespace characters remaining in the stream after parsing the integer (for example, letters or extra digits). If it finds anything, the input is considered invalid.

The conditions age >= 100 || age <= 0 ensure the age is within the range [1, 99].

If any validation step fails, the program prints “be for real!” and repeats the prompt.

Successful Input

When a valid age is provided, the loop exits and the program prints:

You are years old, seems legit! Exit

The program returns 0 to indicate successful execution.

About

Simple C++ console application that prompts the user to enter their age, validates that the input is a number between 1 and 99; otherwise, it displays an error message and re-prompts until a valid age is entered.

Topics

Resources

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published

Languages