<cstdarg>
void va_start ( va_list ap, paramN );
Initialize a variable argument list
Initializes the object of type va_list passed as argument ap to hold the information needed to retrieve the additional arguments after parameter paramN with function va_arg.
A function that executes va_start, shall also execute va_end before it returns.
Parameters
- ap
- Object of type va_list that will hold the information needed to retrieve the additional arguments with va_arg.
- paramN
- Parameter name of the last named parameter in the function definition.
Return Value
none
Example
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/* va_start example */
#include <stdio.h>
#include <stdarg.h>
void PrintFloats ( int amount, ...)
{
int i;
double val;
printf ("Floats passed: ");
va_list vl;
va_start(vl,amount);
for (i=0;i<amount;i++)
{
val=va_arg(vl,double);
printf ("\t%.2f",val);
}
va_end(vl);
printf ("\n");
}
int main ()
{
PrintFloats (3,3.14159,2.71828,1.41421);
return 0;
}
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The function PrintFloats takes as its first parameter, amount, the number of additional arguments, which are then read using the cstdarg macros and printed out with a specific format.
See also
| va_arg | Retrieve next argument (macro) |
| va_end | End using variable argument list (macro) |
| va_list | Type to hold information about variable arguments (type) |
| vsprintf | Print formatted variable argument list to string (function) |
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