perror, gerror, ierrno: Get System Error Messages

These routines perform the following functions:

perror: Print Message to Logical Unit 0, stderr

The subroutine is called by:

Example 1:

    call perror( "file is for formatted I/O" ) 

gerror: Get Message for Last Detected System Error

The subroutine or function is called by:

Example 2: gerror() as a subroutine:

    character string*30 
    ... 
    call gerror ( string ) 
    write(*,*) string 

Example 3: gerror() as a function; string not used:

    character gerror*30, z*30 
    ... 
    z = gerror( ) 
    write(*,*) z 

ierrno: Get Number for Last Detected System Error

The function is called by:

This number is updated only when an error actually occurs. Most routines and I/O statements that might generate such errors return an error code after the call; that value is a more reliable indicator of what caused the error condition.

Example 4: ierrno():

    INTEGER*4 ierrno, n 
    ... 
    n = ierrno() 
    write(*,*) n 

See also intro(2) and perror(3).

Note:

• string in the call to perror cannot be longer than 127 characters.

• The length of the string returned by gerror is determined by the calling program.

• Runtime I/O error codes for f77 and f90 are listed in the Fortran User's Guide.