macro
<cstdarg>

va_copy

void va_copy (va_list dest, va_list src);
Copy variable argument list
Initializes dest as a copy of src (in its current state).

The next argument to be extracted from dest is the same as the one that would be extracted from src.

A function that invokes va_copy , shall also invoke va_end on dest before it returns.

Parameters

dest
Uninitialized object of type va_list .
After the call, it carries the information needed to retrieve the same additional arguments as src.
If dest has already been passed as first argument to a previous call to va_start or va_copy , it shall be passed to va_end before calling this function.
src
Object of type va_list that already carries information to retrieve additional arguments with va_arg (i.e., it has already been passed as first argument to va_start or va_copy ans has not yet been released with va_end ).

Return Value

none

Example

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/* va_copy example */
#include <stdio.h> /* printf, vprintf*/
#include <stdlib.h> /* malloc */
#include <string.h> /* strlen, strcat */
#include <stdarg.h> /* va_list, va_start, va_copy, va_arg, va_end */
/* print ints until a zero is found: */
void PrintInts (int first,...)
{
 char * buffer;
 const char * format = "[%d] ";
 int count = 0;
 int val = first;
 va_list vl,vl_count;
 va_start(vl,first);
 
 /* count number of arguments: */
 va_copy(vl_count,vl);
 while (val != 0) {
 val=va_arg(vl_count,int);
 ++count;
 }
 va_end(vl_count);
 
 /* allocate storage for format string: */
 buffer = (char*) malloc (strlen(format)*count+1);
 buffer[0]='0円';
 
 /* generate format string: */
 for (;count>0;--count) {
 strcat (buffer,format);
 }
 
 /* print integers: */
 printf (format,first);
 vprintf (buffer,vl);
 
 va_end(vl);
}
int main ()
{
 PrintInts (10,20,30,40,50,0);
 return 0;
}

Output:
[10] [20] [30] [40] [50] [0]


See also

va_start
Initialize a variable argument list (macro)
va_arg
Retrieve next argument (macro)
va_end
End using variable argument list (macro)
va_list
Type to hold information about variable arguments (type)

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