std::overflow_error

From cppreference.com
< cpp‎ | error
C++
Diagnostics library
Defined in header <stdexcept>
class overflow_error;

Defines a type of object to be thrown as exception. It can be used to report arithmetic overflow errors (that is, situations where a result of a computation is too large for the destination type).

The only standard library component that throws this exception is std::bitset::to_ulong.

(until C++11)

The only standard library components that throw this exception are std::bitset::to_ulong and std::bitset::to_ullong

(since C++11)

The mathematical functions of the standard library components do not throw this exception (mathematical functions report overflow errors as specified in math_errhandling). Third-party libraries, however, use this. For example, boost.math throws std::overflow_error if boost::math::policies::throw_on_error

cpp/error/exception cpp/error/runtime error std-overflow error-inheritance.svg

Inheritance diagram

Member functions

(constructor)
 constructs a new overflow_error object with the given message
(public member function)
operator=
 replaces the overflow_error object
(public member function)

std::overflow_error::overflow_error

overflow_error( const std::string & what_arg ) ;
(1)
overflow_error( const char* what_arg );
 (2)
overflow_error( const overflow_error& other );
 (3) (noexcept since C++11)
1) Constructs the exception object with what_arg as explanatory string. After construction, std::strcmp (what( ), what_arg.c_str ( ) ) == 0
2) Constructs the exception object with what_arg as explanatory string. After construction, std::strcmp (what( ), what_arg) == 0
3) Copy constructor. If *this and other both have dynamic type std::overflow_error then std::strcmp (what( ), other.what ( ) ) == 0

Parameters

what_arg - explanatory string
other - another exception object to copy

Exceptions

1,2) May throw std::bad_alloc.

Notes

Because copying std::overflow_error 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&&

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

After the resolution of LWG issue 471 what()

std::overflow_error::operator=

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

Assigns the contents with those of other. If *this and other both have dynamic type std::overflow_error then std::strcmp (what( ), other.what ( ) ) == 0

Parameters

other - another exception object to assign with

Return value

*this

Notes

After the resolution of LWG issue 471 what()

Inherited from std::runtime_error


Inherited from std::exception

Member functions

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

Example

Run this code
#include <iostream>
#include <limits>
#include <stdexcept>
#include <utility>
 
template<typename T, int N>
    requires (N > 0) /*...*/
class Stack
{
    int top_{-1};
    T data_[N];
 
public:
    [[nodiscard]] bool empty() const { return top_ == -1; }
 
    void push(T x)
    {
        if (top_ == N - 1)
            throw std::overflow_error("Stack overflow!");
        data_[++top_] = std::move(x);
    }
 
    void pop()
    {
        if (empty())
            throw std::underflow_error("Stack underflow!");
        --top_;
    }
 
    T const& top() const
    {
        if (empty())
            throw std::overflow_error("Stack is empty!");
        return data_[top_];
    }
};
 
int main()
{
    Stack<int, 4> st;
 
    try
    {
        [[maybe_unused]] auto x = st.top();
    }
    catch (std::overflow_error const& ex)
    {
        std::cout << "1) Exception: " << ex.what() << '\n';
    }
 
    st.push(1337);
    while (!st.empty())
    	st.pop();
 
    try
    {
        st.pop();
    }
    catch (std::underflow_error const& ex)
    {
        std::cout << "2) Exception: " << ex.what() << '\n';
    }
 
    try
    {
        for (int i{}; i != 13; ++i)
            st.push(i);
    }
    catch (std::overflow_error const& ex)
    {
        std::cout << "3) Exception: " << ex.what() << '\n';
    }
}

Output: 

1) Exception: Stack is empty!
2) Exception: Stack underflow!
3) Exception: Stack overflow!

Defect reports

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

DR Applied to Behavior as published Correct behavior
LWG 254 C++98 the constructor accepting const char* was missing added
LWG 471 C++98 the explanatory strings of std::overflow_error's
copies were implementation-defined 		they are the same as that of the
original std::overflow_error object
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/error/overflow_error&oldid=160614