how to call functions

aizkorri · 05-22-2002, 05:07 AM

Hello, I've done a simple app that gives some data as output and I have put it in /usr/bin. /usr/bin/writedata

How can I call it from a program?

int main(int argc, char* argv[]) {
writedata;
}

And of course it says that doesn't know what's writedata.
Some Include that I do not know?
Thanks,
regards,
Aizkorri

gui10 · 05-22-2002, 05:20 AM

i think you can just use the system(your_argument) function... like this:

int main() {
system("writedata");
return 0;
}

theheapWalker · 12-20-2017, 07:17 AM

to call a function in C you use paranthesis after the name of the function.

so a function call would be the following:

writedata();

option 1 ----------------------------------------------------------------

to get items of data from writedata()
you can use the return value.
some thing like:

Code:

   int a_value;

   a_value = writedata();

option 2 ----------------------------------------------------------------

alternatively, have writedata() use a global variable to store
a pointer to a data structure to hold the results from writedata().

global variables are declare before main() in the file.

something like:

Code:

   unsigned int* apointer; /* a variable with global scope declared before main */

   int main(int argc, char* argv[]) {
   writedata;
   }


  writedata()
  {
  apointer = &adatastructure;
  }

if something is not true in this post let me know.

I hope this post aids some-one. considering the threads age.

NevemTeve · 12-20-2017, 08:33 AM

As it is an old topic, you should use [code] and [/code] tags when you post code in it.

sundialsvcs · 12-20-2017, 08:49 AM

Meh ... Keep it simple, simple, simple. You must use parentheses so that "C" knows that it's a function and that you're making a function-call here. (Enclose any required parameters in the parentheses, of course, but the parentheses are syntactically required even if there are no arguments.)

Let the function be the master of its own affairs. If it needs a buffer, it should simply malloc() (or "calloc") one, then be sure to dispose of it. Anyone else should be able to call it, and not particularly care how it does its thing.

theheapWalker · 12-20-2017, 12:40 PM

Thanks NevemTeve for mentioning about the tags.
The post looks better.

suicidaleggroll · 12-20-2017, 01:17 PM

This thread is 15 years old. Within the last day you also resurrected a 16 year old thread.

Please pay attention to the date of the thread before contributing to it. When a thread is this old, there's a very good chance that not a single person who took part in it originally is still an active member of the forum.

astrogeek · 12-20-2017, 01:20 PM

@theheapWalker:

You continue to exhibit a pattern of seeking out old posts and replying to them without providing any useful information or questions of your own.

If you have questions of your own please post them to your own thread with proper context. Please see the Site FAQ for guidance in participation on this forum.

If this pattern continues your posting privileges may be suspended.