Editing Variadic function (section)

===In C++===
The basic variadic facility in C++ is largely identical to that in C. The only difference is in the syntax, where the comma before the ellipsis can be omitted. C++ allows variadic functions without [[named parameter]]s but provides no way to access those arguments since <code>va_start</code> requires the name of the last fixed argument of the function. <!-- When C23 is released the text should be updated to reflect that this is a difference between the languages. When C++26 ports the one argument va_start to C++ (https://wg21.link/p2537) this should be updated again. See also the C section of the article. -->

<syntaxhighlight lang="c++">
#include <iostream>
#include <cstdarg>

void simple_printf(const char* fmt...)      // C-style "const char* fmt, ..." is also valid
{
    va_list args;
    va_start(args, fmt);
 
    while (*fmt != '\0') {
        if (*fmt == 'd') {
            int i = va_arg(args, int);
            std::cout << i << '\n';
        } else if (*fmt == 'c') {
            // note automatic conversion to integral type
            int c = va_arg(args, int);
            std::cout << static_cast<char>(c) << '\n';
        } else if (*fmt == 'f') {
            double d = va_arg(args, double);
            std::cout << d << '\n';
        }
        ++fmt;
    }
 
    va_end(args);
}

int main()
{
    simple_printf("dcff", 3, 'a', 1.999, 42.5); 
}
</syntaxhighlight>

[[Variadic templates]] (parameter pack) can also be used in C++ with language built-in [[Fold (higher-order function)|fold expressions]].

<syntaxhighlight lang="c++">
#include <iostream>

template <typename... Ts>
void foo_print(Ts... args) 
{
    ((std::cout << args << ' '), ...);
}

int main()
{
    std::cout << std::boolalpha;
    foo_print(1, 3.14f); // 1 3.14
    foo_print("Foo", 'b', true, nullptr); // Foo b true nullptr
}
</syntaxhighlight>

The [[CERT Coding Standards]] for C++ strongly prefers the use of [[variadic templates]] (parameter pack) in C++ over the C-style variadic function due to a lower risk of misuse.<ref>{{cite web |title=DCL50-CPP. Do not define a C-style variadic function |url=https://wiki.sei.cmu.edu/confluence/display/cplusplus/DCL50-CPP}}</ref>