NAME¶

std::invalid_argument - std::invalid_argument

Synopsis¶

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.

std-invalid argument-inheritance.svg

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)
invalid_argument( const invalid_argument& other ); (until C++11)
invalid_argument( const invalid_argument& other ) (3) (since C++11)
noexcept;

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 ) (since C++11)
noexcept;

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

// Run this code

#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