The perror function prints the error message.

Perror prints system error messages

Void perror (const char * s );

Prototype in stdio. h

Note:

Perror prints the error message to the stderr stream (via the console), indicating the system error information of the last library program.

First
Print the string parameter, and then
Is a colon, and then
Is the information corresponding to the current errno value, and the last line feed
. Specify that the transmitted file name is a string parameter.

Use the global variable sys_errlist (defined in stdio. H, extern char * _ cdecl sys_errlist [];)

Array of characters for obtaining information, errno (
Defined in stdio. H,
Extern int _ cdecl errno;) can be used as the subscript of the array to find the string corresponding to the error code. The string itself does not include a line break.

Global variable sys_nerr
(Defined in stdio. H,
Extern int _ cdecl sys_nerr;) contains the number of items in the array

Perror does not return values.

Applicable to Unix systems, defined in ANSI C

# Include <stdio. h>
Int main ()
{
File * FP;
Fp = fopen ("perror. dat", "R ");
If (! FP)
Perror ("unable to open the file ");
Return 0;
}