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va_start

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C++
 
Biblioteca de utilitários
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(C++11)
(C++11)
Os operadores relacionais
Original:
Relational operators
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Pares e tuplas
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Pairs and tuples
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(C++11)
(C++11)
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Troque, avançar e avançar
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Swap, forward and move
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(C++11)
(C++11)
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(C++11)
 
Variadic funções
 
Definido no cabeçalho <cstdarg>
void va_start(va_list ap, parm_n);
A macro va_start permite o acesso aos argumentos variável após o argumento nomeado 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 deve ser chamado com uma instância de um objeto válido va_list ap antes de todas as chamadas para 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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Índice

[editar] Parâmetros

ap -
uma instância do tipo va_list
Original:
an instance of the va_list type
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parm_n -
o parâmetro denominado precede o primeiro parâmetro variável
Original:
the named parameter preceding the first variable parameter
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[editar] Expandiu valor

(Nenhum)
Original:
(none)
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[editar] Exemplo

#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';
}

Saída: 

150

[editar] Veja também
acessa o argumento da função próximo aridade
Original:
accesses the next variadic function argument
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(função macro) [edit]
termina travessia dos argumentos da função variádicos
Original:
ends traversal of the variadic function arguments
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(função macro) [edit]
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