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std::strerror(3) C++ Standard Libary std::strerror(3)

NAME

std::strerror - std::strerror

Synopsis


Defined in header <cstring>
char* strerror( int errnum );


Returns a pointer to the textual description of the system error code errnum,
identical to the description that would be printed by std::perror().


errnum is usually acquired from the errno variable, however the function accepts any
value of type int. The contents of the string are locale-specific.


The returned string must not be modified by the program, but may be overwritten by a
subsequent call to the strerror function. strerror is not required to be
thread-safe. Implementations may be returning different pointers to static read-only
string literals or may be returning the same pointer over and over, pointing at a
static buffer in which strerror places the string.

Parameters


errnum - integer value referring to an error code

Return value


Pointer to a null-terminated byte string corresponding to the errno error code
errnum.

Notes


POSIX allows subsequent calls to strerror to invalidate the pointer value returned
by an earlier call. It also specifies that it is the LC_MESSAGES locale facet that
controls the contents of these messages.


POSIX has a thread-safe version called strerror_r defined. Glibc defines an
incompatible version.

Example

// Run this code


#include <cerrno>
#include <clocale>
#include <cmath>
#include <cstring>
#include <iostream>


int main()
{
const double not_a_number = std::log(-1.0);
std::cout << not_a_number << '\n';


if (errno == EDOM)
{
std::cout << "log(-1) failed: " << std::strerror(errno) << '\n';
std::setlocale(LC_MESSAGES, "de_DE.utf8");
std::cout << "Or, in German, " << std::strerror(errno) << '\n';
}
}

Possible output:


nan
log(-1) failed: Numerical argument out of domain
Or, in German, Das numerische Argument ist ausserhalb des Definitionsbereiches

See also


displays a character string corresponding of the current
perror error to stderr
(function)
E2BIG, EACCES, ..., EXDEV macros for standard POSIX-compatible error conditions
(macro constant)
C documentation for
strerror

2024.06.10 http://cppreference.com