<div>
So assuming the variables are all passed on the stack, va_start returns the address of the first argument and va_arg moves backwards through the list until it gets to the last argument?<br />

</div>


So assuming the variables are all passed on the stack, va_start returns the address of the first argument and va_arg moves backwards through the list until it gets to the last argument?


<div>
yes that is correct, you tell va_start the last fixed parameter(before the optional parameters start). &nbsp;You then tell va_arg the type of variable to get, so it knows the size on the stack. &nbsp;I do not use these macros much, but they do come in handy. &nbsp;<br />

</div>


yes that is correct, you tell va_start the last fixed parameter(before the optional parameters start).  You then tell va_arg the type of variable to get, so it knows the size on the stack.  I do not use these macros much, but they do come in handy.  


<div>
<div class="content wysiwyg-content">
Can anyone explain how va_arg works and give an example?
</div>
</div>


Can anyone explain how va_arg works and give an example?

use of va_arg

C is a general-purpose, imperative computer programming language, supporting structured programming, lexical variable scope and recursion, while a static type system prevents many unintended operations. By design, C provides constructs that map efficiently to typical machine instructions, so it has found lasting use in applications that had formerly been coded in assembly language, including operating systems as well as various application software for computers ranging from supercomputers to embedded systems. It is distinct from C++ (which has its roots in C) and C#, and many later languages have borrowed directly or indirectly from C.