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      va_start

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      <metanoindex/>

       
      C++
       
      Biblioteca de utilitários
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      Os operadores relacionais
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      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)
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      Troque, avançar e avançar
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      Swap, forward and move
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      (C++11)
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      (C++11)
       
      Variadic funções
       
      <tbody>
      Definido no cabeçalho <cstdarg>
      <tbody> </tbody>
      void va_start(va_list ap, parm_n);

      </tbody>

      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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      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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      Expandiu valor

      (Nenhum)
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      (none)
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      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

      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]