va_start

 

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日期和時間

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關係運算符 Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

雙和元組 Original: Pairs and tuples The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

pair

tuple （C++11）

piecewise_construct_t （C++11）

piecewise_construct （C++11）

掉期，遠期和移動 Original: Swap, forward and move The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap

forward （C++11）

move （C++11）

move_if_noexcept （C++11）

declval （C++11）

 

可變參數函數

va_start

va_arg

va_copy

va_end

va_list

 

Defined in header <cstdarg>

void va_start(va_list ap, parm_n);

va_start宏允許訪問的可變參數命名的參數parm_n.

Original:

The va_start macro enables access to the variable arguments following the named argument parm_n.

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va_start一個有效的va_list對象的一個​​實例ap進行任何調用之前，應調用va_arg.

Original:

va_start should be invoked with an instance to a valid va_list object ap before any calls to va_arg.

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參數

ap	-	va_list類型的一個實例 Original: an instance of the va_list type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
parm_n	-	命名的參數前的第一個變數的參數 Original: the named parameter preceding the first variable parameter The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

擴展後的值

（無）

Original:

(none)

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為例

#include <iostream>
#include <cstdarg>
 
int add_nums(int count, ...)
{
    int result = 0;
    va_list args;
    va_start(args, count);
    for (int i = 0; i < count; ++i) {
        result += va_arg(args, int);
    }
    return result;
}
 
int main()
{
    std::cout << add_nums(4, 25, 25, 50, 50) << '\n';
}

Output:

150

另請參閱

va_arg	訪問下一個可變參數函數的參數 Original: accesses the next variadic function argument The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函數宏）
va_end	結束遍歷可變參數函數的參數 Original: ends traversal of the variadic function arguments The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函數宏）