您可能对逻辑有很多误解.如果您希望能够从作为第一个参数给出的文件名中进行读取，或者如果没有给出任何参数，则可以从stdin中进行读取，则可以创建一个函数，该函数从输入流中读取string并仅输出所有以a分隔的单词通过将istream引用传递给函数并传递打开的ifstream或std::cin来分隔空格(专门处理第一个单词).

You may be overthinking the logic quite a bit. If you want to be able to read from the filename given as the first argument or from stdin if no argument is given, you can create a function that reads a string from the input stream and simply outputs all words separated by a space (handling the first word specially) by passing an istream reference to the function and either passing the open ifstream or std::cin.

一个简短的示例可能如下所示:

A short example could be something like the following:

#include <iostream>
#include <fstream>
#include <string>

void squishws (std::istream& in)
{
    bool first = true;
    std::string str;

    while (in >> str)   /* while words read */
        if (first) {    /* no space before 1st word */
            std::cout << str;
            first = false;
        }
        else            /* output remaining words with 1 space */
            std::cout << " " << str;

    std::cout << "\n";  /* tidy up with newline */

}

int main (int argc, char **argv) {

    if (argc > 1) {     /* read from file if given as argument */
        std::ifstream f (argv[1]);
        if (f.is_open()) 
            squishws (f);
        else {
            std::cerr << "error: file open failed.\n";
            return 1;
        }
    }
    else {  /* read from stdin */
        squishws (std::cin);
    }

    return 0;
}

您可以根据需要添加输出文件引用，也可以直接在命令行上将输出重定向到输出文件.

You can add an output file reference, as required, or simply redirect the output to an output file on the command line.

示例输入文件

$ cat dat/wswords.txt
this       is         a

file    with


multiple

whitespace.

使用/输出示例

$ ./bin/file_rmwhitespace < dat/wswords.txt
this is a file with multiple whitespace.