Login or Register to Ask a Question and Join Our Community

Sponsored Content
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...
 

10 More Discussions You Might Find Interesting

1. Programming

c++ calling main() function

i just finished a project for a c++ class that i wrote at home on my computer, compiled with gcc. when i brought the code into school it would not compile, it would complain that cannot call main() function. at school we use ancient borland c++ from 1995. anyway my program has 20 different... (3 Replies)
Discussion started by: norsk hedensk
3 Replies

2. Programming

Return value (int) from main to calling shell

What is the sytax to return an int from C program main back to calling shell? #!/usr/bin/ksh typeset -i NO_RECS $NO_RECS=process_file # Process file is a C program that is set up to return an int from main. The #program complies with no issues, but an error is generated when the... (3 Replies)
Discussion started by: flounder
3 Replies

3. Programming

main function

Is it possible to execute any function before main() function in C or C++. (6 Replies)
Discussion started by: arun.viswanath
6 Replies

4. Programming

signal handling while in a function other than main

Hi, I have a main loop which calls a sub loop, which finally returns to the main loop itself. The main loop runs when a flag is set. Now, I have a signal handler for SIGINT, which resets the flag and thus stops the main loop. Suppose I send SIGINT while the program is in subloop, I get an error... (1 Reply)
Discussion started by: Theju
1 Replies

5. Shell Programming and Scripting

problem in awk int() function

awk -vwgt=$vWeight -vfac=$vFactor ' BEGIN { printf("wgt:" wgt "\n"); printf("factor:" fac "\n"); total = sprintf("%.0f", wgt * fac); total2 = sprintf("%.0f", int(wgt * fac)); printf("total:" total "\n"); printf("total2:" total2 "\n"); } ' if vWeight=326.4 vFactor=100 the result... (2 Replies)
Discussion started by: qa.bingo
2 Replies

6. Shell Programming and Scripting

Awk issue using int function

Hi, I am having issue with awk command . This command is running in the command prompt but inside a shell script. awk -F'| ' 'int($1)==$1 && int($3) ==$3' int_check.txt $cat int_check.txt 123|abc|123x 234|def|345 When i run it inside a shell script i am getting the error "bailing... (5 Replies)
Discussion started by: ashwin3086
5 Replies

7. Shell Programming and Scripting

Perl int function solved

Hello, I have the below perl function int to return the integer value from the expression but it is not. I am not sure if something misses out here. Any help on this? Thanks in advance. # Code sample Start my $size = int (`1134 sample_text_here`); print "$size \n"; # Code end ----------... (0 Replies)
Discussion started by: nmattam
0 Replies

8. Programming

Handle int listen(int sockfd, int backlog) in TCP

Hi, from the manual listen(2): listen for connections on socket - Linux man page It has a parameter called backlog and it limits the maximum length of queue of pending list. If I set backlog to 128, is it means no more than 128 packets can be handled by server? If I have three... (3 Replies)
Discussion started by: sehang
3 Replies

9. Programming

How to access argv[x] from another function other than main???

Hi friends, when I am passing arguments to main, I want another function to be able to have access to that function, the problem is that I am creating athread, which has a function like void *xyz(void *), how can pass the refernce of argv to this function, if you see my program, you will better... (2 Replies)
Discussion started by: gabam
2 Replies

10. UNIX for Beginners Questions & Answers

A function that refuses to run anywhere else but main()

Hi. I have some code, that for some reason, I could not post it here in this post. Here's the address for it: #if 0 shc Version 4.0.1, Generic Shell Script Compiler GNU GPL Version 3 Md - Pastebin.com First off, I used "shc" to convert the code from shell script to C. And The... (6 Replies)
Discussion started by: ignatius
6 Replies

LEARN ABOUT CENTOS

papi_event_name_to_code

PAPI_event_name_to_code(3)					       PAPI						PAPI_event_name_to_code(3)

NAME

       PAPI_event_name_to_code -

       Convert a name to a numeric hardware event code.

SYNOPSIS

Detailed Description
       @par C Interface:
       int PAPI_event_name_to_code( char * EventName, int * EventCode );

       PAPI_event_name_to_code is used to translate an ASCII PAPI event name
       into an integer PAPI event code.

       @param *EventCode
	   The numeric code for the event.
       @param *EventName
	   A string containing the event name as listed in PAPI_presets or discussed in PAPI_native.

       @retval PAPI_EINVAL
	   One or more of the arguments is invalid.
       @retval PAPI_ENOTPRESET
	   The hardware event specified is not a valid PAPI preset.
       @retval PAPI_ENOINIT
	   The PAPI library has not been initialized.
       @retval PAPI_ENOEVNT
	   The hardware event is not available on the underlying hardware.

       @par Examples:

       *   int EventCode, EventSet = PAPI_NULL;
       *   // Convert to integer
       *   if ( PAPI_event_name_to_code( "PAPI_TOT_INS", &EventCode ) != PAPI_OK )
       *   handle_error( 1 );
       *   // Create the EventSet
       *   if ( PAPI_create_eventset( &EventSet ) != PAPI_OK )
       *   handle_error( 1 );
       *   // Add Total Instructions Executed to our EventSet
       *   if ( PAPI_add_event( EventSet, EventCode ) != PAPI_OK )
       *   handle_error( 1 );
       *

       See Also:
	   PAPI_event_code_to_name

	   PAPI_remove_event

	   PAPI_get_event_info

	   PAPI_enum_event

	   PAPI_add_event

	   PAPI_add_named_event

	   PAPI_presets

	   PAPI_native

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

Version 5.2.0.0 						  Tue Jun 17 2014					PAPI_event_name_to_code(3)
All times are GMT -4. The time now is 08:12 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy