C ++:在文件中向后移动 [英] C++: Moving backwards in a file

问题描述

我想向后移动并提取出现"new"的整个行.

I want to move backwards and extract the whole line in which ''new'' occurs.

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

using namespace std;

int main()
  {
char word[30];
  string filename;
  
  cout << "Name your file> ";
  getline( cin, filename );

  fstream file( filename.c_str() );
  if (!file)
    {
    cout << "I could not open the file. Fooey.\n";
    return EXIT_FAILURE;
    }
  else 
    {
    string line;
    
    while (!file.eof())
      {
          file >> word;
		if(strcmpi(word,"new")==0)		
           {
			/*getline( file, line );
				cout << line;*/
		}

	 
     
      }
    file.close();
    }

  return EXIT_SUCCESS;
  }

推荐答案

为什么不逐行阅读文件(使用字符串?这样(成功完成找到 [

Why don''t you read the file line by line (using std::getline[^]), and search the "new" string inside the line? This way (on successful find[^] call) you already have the needed line.


[updated]
Something like this (not tested):

do
{
  getline( file, line);
  if ( ! file.good() ) break; // end of file or some other error
  if ( line.find("new") != string::npos)
  {
    // found: here 'line' is the wanted line.
  }
} while ( true );

[/updated]

[/updated]

@cpallini-谢谢您的帮助..请写一些代码片段来解决我的问题.我对编程非常陌生..我尝试了您的建议，但徒劳地..thanx

@cpallini - thanx a lot for your help.. can you please write in a little code snippet to solve my problem. i am very new to programming.. i tried what you suggested but in vain..thanx again

非常感谢.....这是我的第一个任务..taht是为什么我被愚蠢的事情困住了...我真的很感谢您抽出时间来解决我的问题..再次感谢

Thank you so much it worked....Its my first assignment ..taht is why i am getting stuck at stupid things...i am really thankful to you that you took out time for solving my problem ..thanks once again

这篇关于C ++:在文件中向后移动的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！