使用流样式从文件中读取一行

发布于 2024-08-18 03:17:18 字数 369 浏览 2 评论 0原文

我有一个简单的文本文件，其中包含以下内容，

word1 word2

我需要在 C++ 应用程序中读取它的第一行。以下代码有效，……

std::string result;
std::ifstream f( "file.txt" );
f >> result;

但结果变量将等于“word1”。它应该等于“word1 word2”（文本文件的第一行）是的，我知道，我可以使用 readline(f, result) 函数，但是有没有办法做到同样的事情，使用 >>风格。这可能会更漂亮。可能，一些我不知道的操纵器在这里会有用吗？

原文

I have a simple text file, that has following content

word1 word2

I need to read it's first line in my C++ application.
Following code works, ...

std::string result;
std::ifstream f( "file.txt" );
f >> result;

... but result variable will be equal to "word1". It should be equal to "word1 word2" (first line of text file)
Yes, i know, that i can use readline(f, result) function, but is there a way to do the same, using >> style. This could be much more pretty.
Possible, some manipulators, i don't know about, will be useful here ?

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眼眸 2024-08-25 03:17:18

是的，定义一个线类并定义运算符>>对于这堂课。

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


struct Line
{
    std::string line;

    // Add an operator to convert into a string.
    // This allows you to use an object of type line anywhere that a std::string
    // could be used (unless the constructor is marked explicit).
    // This method basically converts the line into a string.
    operator std::string() {return line;}
};

std::istream& operator>>(std::istream& str,Line& line)
{
    return std::getline(str,line.line);
}
std::ostream& operator<<(std::ostream& str,Line const& line)
{
    return str << line.line;
}

void printLine(std::string const& line)
{
    std::cout << "Print Srting: " << line << "\n";
}

int main()
{
    Line    aLine;
    std::ifstream f( "file.txt" );
    f >> aLine;

    std::cout << "Line: " << aLine << "\n";
   printLine(aLine);
}

Yes define a line class and define the operator >> for this class.

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


struct Line
{
    std::string line;

    // Add an operator to convert into a string.
    // This allows you to use an object of type line anywhere that a std::string
    // could be used (unless the constructor is marked explicit).
    // This method basically converts the line into a string.
    operator std::string() {return line;}
};

std::istream& operator>>(std::istream& str,Line& line)
{
    return std::getline(str,line.line);
}
std::ostream& operator<<(std::ostream& str,Line const& line)
{
    return str << line.line;
}

void printLine(std::string const& line)
{
    std::cout << "Print Srting: " << line << "\n";
}

int main()
{
    Line    aLine;
    std::ifstream f( "file.txt" );
    f >> aLine;

    std::cout << "Line: " << aLine << "\n";
   printLine(aLine);
}

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