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

NAME
       std::perror - std::perror

Synopsis
	  Defined in header <cstdio>
	  void perror( const char *s );

	  Prints  a  textual description of the	error code currently stored in
       the system
	  variable errno to stderr.

	  The description is formed by concatenating the following components:

	    * the contents of the null-terminated byte string pointed to by s,
       followed	by ":
	      "	(unless	s is a null pointer or the character pointed to	 by  s
       is the null
	      character)
	    * implementation-defined error message string describing the error
       code stored in
	      errno,  followed	by '\n'. The error message string is identical
       to the result of
	      std::strerror(errno).

Parameters
	  s - pointer to a null-terminated string with explanatory message

Return value
	  (none)

Example
       // Run this code

	#include <cmath>
	#include <cerrno>
	#include <cstdio>

	int main()
	{
	    double not_a_number	= std::log(-1.0);
	    if (errno == EDOM) {
		std::perror("log(-1) failed");
	    }
	    std::printf("%f\n",	not_a_number);
	}

Possible output:
	log(-1)	failed:	Numerical argument out of domain
	nan

See also
	  errno	   macro which expands to POSIX-compatible thread-local	 error
       number variable
		   (macro variable)
	  strerror returns a text version of a given error code
		   (function)

http://cppreference.com		  2022.07.31			std::perror(3)

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<https://man.freebsd.org/cgi/man.cgi?query=std::perror&sektion=3&manpath=FreeBSD+Ports+15.0>

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