std::invalid_argument error in C++

introduction

In C++ programming,std::invalid_argumentis a standard exception, which is usually thrown when a function receives an invalid parameter. This exception isstd::invalid_argumentType, it isstd::exceptionderivative class. This article will explore the cause of this exception and provide several solutions.

1. Problem description

1.1 Error report example

Here is a sample code that could cause this error:

#include <iostream>
#include <stdexcept>
int main() {
    int x = -1;
    if (x < 0) {
        throw std::invalid_argument("x cannot be negative");
    }
    std::cout << "x is positive" << std::endl;
    return 0;
}

When running the above code you will get the following error:

terminate called after throwing an instance of 'std::invalid_argument'
  what():  x cannot be negative

1.2 Error report analysis

This error indicates thatmainIn the function, variablexChecked whether it is less than 0, if so, thrownstd::invalid_argumentException.std::invalid_argumentExceptions are usually thrown when the parameters do not meet the function requirements.

1.3 Solutions

To solve this problem, we need to make sure that the parameters passed to the function are valid and that it is properly handled when the exception occurs. Here are some solutions.

2. Solution

2.1 Method 1: Catch and handle exceptions

Capture in codestd::invalid_argumentException and handle it appropriately.

#include <iostream>
#include <stdexcept>
int main() {
    try {
        int x = -1;
        if (x < 0) {
            throw std::invalid_argument("x cannot be negative");
        }
        std::cout << "x is positive" << std::endl;
    } catch (const std::invalid_argument& e) {
        std::cerr << "Error: " << () << std::endl;
    }
    return 0;
}

2.2 Method 2: Parameter verification

Add parameter verification logic inside the function to ensure that the parameters are valid before the function call.

#include <iostream>
#include <stdexcept>
void validatePositive(int x) {
    if (x < 0) {
        throw std::invalid_argument("x cannot be negative");
    }
}
int main() {
    int x = -1;
    try {
        validatePositive(x);
        std::cout << "x is positive" << std::endl;
    } catch (const std::invalid_argument& e) {
        std::cerr << "Error: " << () << std::endl;
    }
    return 0;
}

2.3 Method 4: Use assertions

Use assertions to ensure that the parameters are valid during development.

#include <iostream>
#include <stdexcept>
#include <cassert>
int main() {
    int x = -1;
    assert(x >= 0 && "x cannot be negative");
    std::cout << "x is positive" << std::endl;
    return 0;
}

3. Other solutions

• Always check whether the parameters passed to the function are valid when writing code.
• Use the IDE or code editor's checking feature to identify potential invalid parameters.
• During the code review process, be careful to find situations that may lead to invalid parameters.

4. Summary

In this article, we discussstd::invalid_argumentThe cause of the exception and several solutions are provided. We can avoid such errors by ensuring that the argument passed to the function is valid and that it is properly handled when the exception occurs.

Next time you encounter a similar error, you can review the solutions mentioned in this article and choose the most appropriate method according to the specific situation. Hope this information can help you quickly resolve the problems you encounter!

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