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std::invalid_argument - cppreference.com

Defines a type of object to be thrown as exception. It reports errors that arise because an argument value has not been accepted.

This exception is thrown by std::bitset::bitset, and the std::stoi and std::stof families of functions.

However, std::invalid_argument objects generally cannot be constexpr, because any dynamically allocated storage must be released in the same evaluation of constant expression.

Inheritance diagram

invalid_argument( const char* what_arg );

invalid_argument( const invalid_argument& other );

Constructs the exception object with

as explanatory string. After construction,

.

Constructs the exception object with

as explanatory string. After construction,

.

Copy constructor. If

and

both have dynamic type

then

. No exception can be thrown from the copy constructor.

Because copying std::invalid_argument is not permitted to throw exceptions, this message is typically stored internally as a separately-allocated reference-counted string. This is also why there is no constructor taking std::string&&: it would have to copy the content anyway.

Before the resolution of LWG issue 254, the non-copy constructor can only accept std::string. It makes dynamic allocation mandatory in order to construct a std::string object.

After the resolution of LWG issue 471, a derived standard exception class must have a publicly accessible copy constructor. It can be implicitly defined as long as the explanatory strings obtained by what() are the same for the original object and the copied object.

invalid_argument& operator=( const invalid_argument& other );

Assigns the contents with those of other. If *this and other both have dynamic type std::invalid_argument then std::strcmp(what(), other.what()) == 0 after assignment. No exception can be thrown from the copy assignment operator.

*this

After the resolution of LWG issue 471, a derived standard exception class must have a publicly accessible copy assignment operator. It can be implicitly defined as long as the explanatory strings obtained by what() are the same for the original object and the copied object.

The purpose of this exception type is similar to the error condition std::errc::invalid_argument (thrown in std::system_error from member functions of std::thread) and the related errno constant EINVAL.

#include <bitset>
#include <iostream>
#include <stdexcept>
#include <string>
 
int main()
{
    try
    {
        std::bitset<4>{"012"}; // Throws: only '0' or '1' expected
    }
    catch (std::invalid_argument const& ex)
    {
        std::cout << "#1: " << ex.what() << '\n';
    }
 
    try
    {
        [[maybe_unused]] int f = std::stoi("ABBA"); // Throws: no conversion
    }
    catch (std::invalid_argument const& ex)
    {
        std::cout << "#2: " << ex.what() << '\n';
    }
 
    try
    {
        [[maybe_unused]] float f = std::stof("(3.14)"); // Throws: no conversion
    }
    catch (std::invalid_argument const& ex)
    {
        std::cout << "#3: " << ex.what() << '\n';
    }
}

Possible output:

#1: bitset string ctor has invalid argument
#2: stoi: no conversion
#3: stof: no conversion

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

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