C ++ fstream函数读取行而不提取? [英] C++ fstream function that reads a line without extracting?

问题描述

在C ++中，fstream库(或任何库)中是否有一个函数可以让我读取行号为'\ n'的定界符而无需提取?

In C++, is there a function in the fstream library (or any library) that allows me to read a line to a delimiter of '\n' without extracting?

我知道peek()函数允许程序在不提取信息的情况下窥视"其读入的下一个字符，但我需要类似peek()的函数来执行此操作，但需要整行.

I know the peek() function allows the program to 'peek' at the next character its reading in without extracting but I need a peek() like function that does that but for a whole line.

推荐答案

您可以将getline，tellg和seekg组合使用.

You can do this with a combination of getline, tellg and seekg.

#include <fstream>
#include <iostream>
#include <ios>


int main () {
    std::fstream fs(__FILE__);
    std::string line;

    // Get current position
    int len = fs.tellg();

    // Read line
    getline(fs, line);

    // Print first line in file
    std::cout << "First line: " << line << std::endl;

    // Return to position before "Read line".
    fs.seekg(len ,std::ios_base::beg);

    // Print whole file
    while (getline(fs ,line)) std::cout << line << std::endl;
}

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