Variable number of parameters in function in C++

c, c++, syntax, variadic-functions

Solution

These are called Variadic functions. Wikipedia lists example code for C++.

To portably implement variadic functions in the C programming language, the standard stdarg.h header file should be used. The older varargs.h header has been deprecated in favor of stdarg.h. In C++, the header file `cstdarg` should be used.

To create a variadic function, an ellipsis (`...`) must be placed at the end of a parameter list. Inside the body of the function, a variable of type `va_list` must be defined. Then the macros `va_start(va_list, last fixed param)`, `va_arg(va_list, cast type)`, `va_end(va_list)` can be used. For example:

#include <stdarg.h>

double average(int count, ...)
{
    va_list ap;
    int j;
    double tot = 0;
    va_start(ap, count); //Requires the last fixed parameter (to get the address)
    for(j=0; j<count; j++)
        tot+=va_arg(ap, double); //Requires the type to cast to. Increments ap to the next argument.
    va_end(ap);
    return tot/count;
}

Problem

How I can have variable number of parameters in my function in C++. Analog in C#: ``` public void Foo(params int[] a) { for (int i = 0; i < a.Length; i++) Console.WriteLine(a[i]); } public void UseFoo() { Foo(); Foo(1); Foo(1, 2); } ``` Analog in Java: ``` public void Foo(int... a) { for (int i = 0; i < a.length; i++) System.out.println(a[i]); } public void UseFoo() { Foo(); Foo(1); Foo(2); } ```

Original source

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