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std::tmpnam

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tmpnam
 
Definido no cabeçalho <cstdio>
char* tmpnam( char* filename );
Cria um nome de arquivo único que não nomeia um arquivo atualmente existente, e armazena-lo na cadeia de caracteres apontada por filename. A função é capaz de gerar até TMP_MAX de nomes de ficheiros originais, mas alguns ou todos eles podem já estar em uso, e não os valores de retorno, assim, adequados.
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Creates an unique filename that does not name a currently existing file, and stores it in the character string pointed to by filename. The function is capable of generating up to TMP_MAX of unique filenames, but some or all of them may already be in use, and thus not suitable return values.
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Índice

[editar] Parâmetros

filename -
ponteiro para o conjunto de caracteres capazes de segurar os bytes menos L_tmpnam, para ser usado como um buffer de resultado. Se NULL é passado, um ponteiro para um buffer interno estático é retornado .
Original:
pointer to the character array capable of holding at least L_tmpnam bytes, to be used as a result buffer. If NULL is passed, a pointer to an internal static buffer is returned.
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[editar] Valor de retorno

filename se filename não era NULL. Caso contrário, um ponteiro para um buffer interno estático é retornado. Se nenhum nome adequado pode ser gerado, NULL é retornado.
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filename if filename was not NULL. Otherwise a pointer to an internal static buffer is returned. If no suitable filename can be generated, NULL is returned.
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[editar] Notas

Quando chamado com o argumento de ponteiro nulo, esta função modifica um objeto global. Se outra thread chama std::tmpnam com o argumento de ponteiro nulo, ao mesmo tempo, o comportamento é indefinido devido a uma corrida de dados.
Original:
When called with null pointer argument, this function modifies a global object. If another thread calls std::tmpnam with null pointer argument at the same time, the behavior is undefined due to a data race.
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Embora os nomes gerados por std::tmpnam são difíceis de adivinhar, é possível que um arquivo com esse nome é criado por outro processo entre os retornos momento std::tmpnam eo momento este programa tenta usar o nome retornado para criar um arquivo. O std::tmpfile função padrão ea função POSIX mkstemp não tem esse problema.
Original:
Although the names generated by std::tmpnam are difficult to guess, it is possible that a file with that name is created by another process between the moment std::tmpnam returns and the moment this program attempts to use the returned name to create a file. The standard function std::tmpfile and the POSIX function mkstemp do not have this problem.
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[editar] Exemplo

#include <iostream>
#include <cstdio>
#include <string>
int main()
{
    std::string name1 = std::tmpnam(nullptr);
    std::cout << "temporary file name: " << name1 << '\n';
 
    char name2[L_tmpnam];
    if(std::tmpnam(name2))
        std::cout << "temporary file name: " << name2 << '\n';
}

Potencial saída: 

temporary file name: /tmp/fileDjwifs
temporary file name: /tmp/fileEv2bfW

[editar] Veja também
cria e abre um temporário, arquivo auto de remoção
Original:
creates and opens a temporary, auto-removing file
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(função) [edit]
Documentação C para tmpnam
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