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std::invalid_argument

Defined in header `<stdexcept>`
class invalid_argument;

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.

Inheritance diagram.

Member functions

(constructor)	constructs a new `invalid_argument` object with the given message (public member function)
operator=	replaces the `invalid_argument` object (public member function)
what	returns the explanatory string (public member function)

std::invalid_argument::invalid_argument

invalid_argument( const std::string& what_arg );	(1)
invalid_argument( const char* what_arg );	(2)	(since C++11)
	(3)
invalid_argument( const invalid_argument& other );		(until C++11)
invalid_argument( const invalid_argument& other ) noexcept;		(since C++11)

1-2) Constructs the exception object with what_arg as explanatory string that can be accessed through what().

3) Copy constructor. If *this and other both have dynamic type std::invalid_argument then std::strcmp(what(), other.what()) == 0. (since C++11)

Parameters

what_arg	-	explanatory string
other	-	another exception object to copy

Exceptions

1-2) May throw std::bad_alloc

Notes

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.

std::invalid_argument::operator=

invalid_argument& operator=( const invalid_argument& other );		(until C++11)
invalid_argument& operator=( const invalid_argument& other ) noexcept;		(since C++11)

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. (since C++11).

Parameters

other

another exception object to assign with

Return value

*this.

std::invalid_argument::what

virtual const char* what() const throw();		(until C++11)
virtual const char* what() const noexcept;		(since C++11)

Returns the explanatory string.

Parameters

(none).

Return value

Pointer to a null-terminated string with explanatory information. The string is suitable for conversion and display as a std::wstring. The pointer is guaranteed to be valid at least until the exception object from which it is obtained is destroyed, or until a non-const member function (e.g. copy assignment operator) on the exception object is called.

Notes

Implementations are allowed but not required to override what().

Inherited from std::logic_error

Inherited from std::exception

Member functions

(destructor) [virtual]	destroys the exception object (virtual public member function of `std::exception`)
what [virtual]	returns an explanatory string (virtual public member function of `std::exception`)

Notes

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.

Example

#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

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