Returns a pointer to the textual description of the system error codeerrnum, identical to the description that would be printed bystd::perror().

errnum is usually acquired from theerrno variable, however the function accepts any value of typeint. 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 thestrerror 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 whichstrerror places the string.

[edit]Parameters

[edit]Return value

Pointer to a null-terminated byte string corresponding to theerrno error codeerrnum.

[edit]Notes

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

POSIX has a thread-safe version calledstrerror_r defined. Glibcdefines an incompatible version.

[edit]Example

#include <cerrno>#include <clocale>#include <cmath>#include <cstring>#include <iostream> int main(){constdouble 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';}}

nanlog(-1) failed: Numerical argument out of domainOr, in German, Das numerische Argument ist ausserhalb des Definitionsbereiches

[edit]See also

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