When to define functions in C? Post: 302895174

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Top Forums Programming When to define functions in C? Post 302895174 by jim mcnamara on Friday 28th of March 2014 11:27:43 PM

03-29-2014

Registered User

The actual function code has to precede the function that calls it. So if main() is below all of the functions that main() calls, your idea will work. Functions can be coded (placed) anywhere in the source file, top or bottom of the code file.

Where all of this becomes messy is in the concept of a call tree. Well written functions do one thing very well. So it is desirable for some bit of repeated logic to be placed in a function and called from different places in the code. In this instance you could have problems with placing a function in your code physically before it gets called by another function, because it may be called in lots of others functions. The model you don't seem to like overcomes this issue. You no longer need to worry about the order of functions written in your code when you create function "prototypes". And place them near the start of the source file, before any function code.

It is typical to place all function prototypes (or whatever you wish to call them) at the very beginning of the file, after the #include section. This also allows you to place this stuff in a separate header file. That lets you then call a bunch of the code in your current code file in other C program files. This is the idea behind a code library: DRY coding - don't repeat yourself. Write a function once, use it forever.

Linking them is beyond the scope of this little message.

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LEARN ABOUT DEBIAN

ns_masterlock

Ns_Master(3aolserver)					   AOLserver Library Procedures 				     Ns_Master(3aolserver)

__________________________________________________________________________________________________________________________________________________

NAME

       Ns_MasterLock, Ns_MasterUnlock - Enter and leave the single master critical section lock

SYNOPSIS

       #include "ns.h"

       void
       Ns_MasterLock(void)

       void
       Ns_MasterUnlock(void)
_________________________________________________________________

DESCRIPTION

       The  single  master  critical  section  lock is used throughout the core server to protect portions of code from being run by more than one
       thread at a time. These are convenience functions which actually make calls to Ns_CsEnter and Ns_CsLeave to perform the locking and unlock-
       ing function.

       You  should not use these functions in your modules. To protect critical sections in your modules you should create and initialize your own
       named locks, then wrap your critical sections with calls to Ns_CsEnter and Ns_CsLeave.

       Ns_MasterLock()

	      Enter the single master lock. The thread that holds this lock is guaranteed exclusive access to the section of code that follows the
	      call  to	Ns_MasterLock.	Other  threads that attempt to enter the master critical section while another thread owns the master lock
	      will block until the owning thread releases the master lock.

	      Be extremely careful with code you place within the master critical section. If the thread that owns the master lock blocks for  any
	      reason  while in the master critical section, other threads that need to enter that section of code will block until the master lock
	      is released.

       Ns_MasterUnlock()

	      Leave the single master critical section. The thread that owns the lock must release it after the critical section of code has  com-
	      pleted so that other threads may execute the critical section code.

SEE ALSO

       nsd(1), info(n), Ns_CsEnter(3), Ns_CsLeave(3)

KEYWORDS

AOLserver								4.0						     Ns_Master(3aolserver)