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Full Discussion: Function main returning int?
Top Forums Programming Function main returning int? Post 302727113 by jim mcnamara on Monday 5th of November 2012 08:07:54 PM
Old 11-05-2012
Read the main page on waitpid or wait to get more detail.

The return value of a process to the calling is process is the least significant eight bits of the number returned by main(). Which can be seen as signed or unsigned by the parent. So, the valid results from calling wait on a child returns values from 0 to 255 (looked at as unsigned).

By convention 0 means success, as defined in C by EXIT_SUCCESS.

Since main() is an int function you can return any valid int, but is not very useful to return numbers larger than the range I just defined.

Code:
// retval.c
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
     int retval=atoi(argv[1]);
     printf("I am returning %d\n", retval);
     return retval;
}

Compile retval then run it with this script
Code:
#!/bin/ksh
cnt=1
while [ $cnt -le 100000000 ]
do
       retval $cnt
       cnt=$((  $cnt * 10 ))
done

And see what happens...
 

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LEARN ABOUT CENTOS

papi_add_named_event

PAPI_add_named_event(3) 					       PAPI						   PAPI_add_named_event(3)

NAME

       PAPI_add_named_event -

       add PAPI preset or native hardware event by name to an EventSet

SYNOPSIS

Detailed Description
       @par C Interface:
       int PAPI_add_named_event( int EventSet, char *EventName );

       PAPI_add_named_event adds one event to a PAPI EventSet. @n
       A hardware event can be either a PAPI preset or a native hardware event code.
       For a list of PAPI preset events, see PAPI_presets or run the avail test case
       in the PAPI distribution. PAPI presets can be passed to PAPI_query_event to see
       if they exist on the underlying architecture.
       For a list of native events available on current platform, run the papi_native_avail
       utility in the PAPI distribution.

       @param EventSet
	   An integer handle for a PAPI Event Set as created by PAPI_create_eventset.
       @param EventCode
	   A defined event such as PAPI_TOT_INS.

       @retval Positive-Integer
	   The number of consecutive elements that succeeded before the error.
       @retval PAPI_EINVAL
	   One or more of the arguments is invalid.
       @retval PAPI_ENOINIT
	   The PAPI library has not been initialized.
       @retval PAPI_ENOMEM
	   Insufficient memory to complete the operation.
       @retval PAPI_ENOEVST
	   The event set specified does not exist.
       @retval PAPI_EISRUN
	   The event set is currently counting events.
       @retval PAPI_ECNFLCT
	   The underlying counter hardware can not count this event and other events
	   in the event set simultaneously.
       @retval PAPI_ENOEVNT
	   The PAPI preset is not available on the underlying hardware.
       @retval PAPI_EBUG
	   Internal error, please send mail to the developers.

       @par Examples:

       *  char EventName = "PAPI_TOT_INS";
       *   int EventSet = PAPI_NULL;
       *   unsigned int native = 0x0;
       *   if ( PAPI_create_eventset( &EventSet ) != PAPI_OK )
       *   handle_error( 1 );
       *   // Add Total Instructions Executed to our EventSet
       *   if ( PAPI_add_named_event( EventSet, EventName ) != PAPI_OK )
       *   handle_error( 1 );
       *   // Add native event PM_CYC to EventSet
       *   if ( PAPI_add_named_event( EventSet, "PM_CYC" ) != PAPI_OK )
       *   handle_error( 1 );
       *

       @see PAPI_add_event @n
       PAPI_query_named_event @n
       PAPI_remove_named_event.fi

Author
       Generated automatically by Doxygen for PAPI from the source code.

Version 5.2.0.0 						  Tue Jun 17 2014					   PAPI_add_named_event(3)
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