c++ - 无需检查即可将标准输入快速读入缓冲区

Question

我有缓冲区，比方说65536字节长。如何在不进行换行符或'\ 0'字符检查的情况下，尽可能快地(使用IO硬件)将stdin读入该缓冲区。我保证stdin中的字符数将始终与缓冲区匹配。

到目前为止，我有这个:

#include <iostream>
#include <stdio.h>

#define BUFFER_LENGTH 65536

int main()
{
    std::ios::sync_with_stdio(false);
    setvbuf(stdout, NULL, _IONBF, BUFFER_LENGTH);

    char buffer[BUFFER_LENGTH];

    // now read stdin into buffer
    // fast print:
    puts(buffer);    // given buffer is null terminated

    return 0;
}

是否有类似于 puts()的东西可以快速读入缓冲区而不是控制台？

Answer 1

您可以使用C的标准 fread() function:

#include <iostream>
#include <stdio.h>

#define BUFFER_LENGTH 65536

int main()
{
    std::ios::sync_with_stdio(false);
    setvbuf(stdout, NULL, _IONBF, BUFFER_LENGTH);

    // need space to terminate the C-style string
    char buffer[BUFFER_LENGTH + 1];

    // eliminate stdin buffering too
    setvbuf(stdin, NULL, _IONBF, BUFFER_LENGTH);    

    // now read stdin into buffer
    size_t numRead = fread( buffer, 1, BUFFER_LENGTH, stdin );

    // should check for errors/partial reads here

    // fread() will not terminate any string so it
    // has to be done manually before using puts()
    buffer[ numRead ] = '\0';

    // fast print:
    puts(buffer);    // given buffer is null terminated

    return 0;
}