Question

How to handle invalid argument in C++

Answer 1

#include <iostream>
#include <stdexcept>

void printNumber(int num) {
    if (num < 0) {
        throw std::invalid_argument("Negative numbers are not allowed.");
    }
    std::cout << "Number: " << num << std::endl;
}

int main() {
    try {
        printNumber(-8);
    } catch (const std::invalid_argument& e) {
        std::cerr << "Error: " << e.what() << std::endl;
    }
}



/*
run:

ERROR!
Error: Negative numbers are not allowed.

*/

 

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Answer 2

#include <iostream>

bool isValidInput(int num) {
    return num >= 0; 
}

int main() {
    int num;
    std::cout << "Enter a number: ";
    std::cin >> num;

    if (!isValidInput(num)) {
        std::cerr << "Invalid input: Negative numbers are not allowed." << std::endl;
    } else {
        std::cout << "Valid input: " << num << std::endl;
    }
}



/*
run:

Enter a number: -9
Invalid input: Negative numbers are not allowed.

*/

 

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Answer 3

#include <cassert>

void printNumber(int num) {
    assert(num >= 0 && "Number must be non-negative");
    // Write your code here...
}

int main() {
    printNumber(-4); // This will terminate the program in debug mode
}




/*
run:

Enter a number: -9
main.cpp:4: void printNumber(int): Assertion `num >= 0 && "Number must be non-negative"' failed.
Aborted

*/

 

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Answer 4

#include <iostream>
#include <optional>

std::optional<int> safeCalculation(int num) {
    if (num < 0) return std::nullopt;
    return num * 2; // Calculation
}

int main() {
    auto result = safeCalculation(-6);
    
    if (result) {
        std::cout << "Result: " << *result << std::endl;
    } else {
        std::cout << "Invalid argument detected." << std::endl;
    }
}




/*
run:

Invalid argument detected.

*/

 

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