Extarct a word after a particular word in a file in c++

Question

5.00/5 (1 vote)

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C++

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

using namespace std;

int main()
  {
char word[30];
  string filename;
 //map<char,int> mymap;
  //map<char,int>::iterator it;


  
  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 (getline( file, line ))
      {
         if ( line.find("new") != string::npos)
    {
      if ( line.find("int *") != string::npos)
	  {
		//want to catch the pointer in which the memory is allocated  
	  }
    }

	 
     
      }
    file.close();
    }

  return EXIT_SUCCESS;
  }

I am creating a static analyzer to detect memory leaks ..please help

Posted 24-Jan-12 18:25pm

Member 8576081

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4 solutions

Solution 1

I think using Regular Expressions will help you a lot in doing this project :

http://linuxgazette.net/issue27/mueller.html[^]

Henry Spencer's Regexp Engine Revisited[^]

http://www.regular-expressions.info/tutorial.html[^]

There are many C++ libraries for Regular Expression pattern matching. Use google to find more resources about it.

Posted 24-Jan-12 19:13pm

Amir Mahfoozi

Solution 2

You could also use the return value of the call to line.find() which gives the starting position of the string. However your code has a major problem as an analyzer in that not everyone writes using the same conventions. consider the following lines of code:

C++

int *pOne;
int* pTwo;
int  *    // this is a comment
  pThree;

All of these are syntactically correct but you need quite a lot more to be able to recognise them.

Posted 24-Jan-12 22:58pm

Richard MacCutchan

Solution 4

Your code processes a line at a time.

In your example, you have two lines to evaluate.

You're going to need more logic than a simple keyword search to do this.

Essentially you'll need to write a parser that can understand the meaning of statements in context.

I'll throw you a another monkey wrench...

C++

void * p = NULL;

switch(n)
{
case 0:
    p = new CStuff1;
    break;

case 1:
    p = new CStuff2;
    break;

case 2:
    throw("Invalid Value");
    break;

case 3:
    p = new CStuff3;
    break;

default:
    p = NULL;
    break;
}

Posted 27-Jan-12 8:15am

JackDingler

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Member 8576081 · Accepted Answer · 2012-01-26T20:07:00

yes you are right...that is why i did thi to extract the variable name...

C++

  while (getline( file, line ))
    {
       if ( line.find("new") != string::npos)
        {
      temp = line;
      string::iterator It = temp.begin();
while ( *It != '*'  )
  {
      It++;
  }
    It++;
   while ( *It != '='  )
  {

      word = *It;
      It++;
     if (word ==' ')
     {
         continue;

     }

      str = str + word;
   }

but again if the declaration is like this:

C++

int* p ;
p = new int;

the problem still persists..can you help plzzz