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Apr 26th, 2007

Scan File for Comments

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I am trying to write a program that will scan another file for comments only. It will scan for comments of both types, // and /* */, and then print these comments. The code I have written so far works, but it prints the entire code. I would really appreciate a little guidance!

c Syntax (Toggle Plain Text)
 
#include <iostream>
#include <fstream>
using namespace std;
 
int main()
{
           char InFile[80];  // input file name
           char ch;
 
           ifstream InStream;
           cout << "This program reads the content of a file and ";
           cout << "prints only the comments out on the screen." 
           <<    endl;
           cout << "Enter input file name: " ;
           cin >> InFile;
           // Open file for input
 
           InStream.open(InFile, ios::in);
           // ensure file is opened successfully
           if(!InStream)
          {
                    cout << "Error open file " << InFile << endl;
                    return 1;
          }
 
          cout << "Here are the comments of " << InFile << ":\n";
          // Read in each character until eof character is read.
          // Output it to screen.
         while (!InStream.eof()) {
                  //Read each character.
                 InStream.get(ch);    
                 if (!InStream.eof()) 
                 {
                          cout << ch;  //Write to screen
                 }
          }
          InStream.close();
}
 
#include <iostream>
#include <fstream>
using namespace std;
 
int main()
{
           char InFile[80];  // input file name
           char ch;
 
           ifstream InStream;
           cout << "This program reads the content of a file and ";
           cout << "prints only the comments out on the screen." 
           <<    endl;
           cout << "Enter input file name: " ;
           cin >> InFile;
           // Open file for input
 
           InStream.open(InFile, ios::in);
           // ensure file is opened successfully
           if(!InStream)
          {
                    cout << "Error open file " << InFile << endl;
                    return 1;
          }
 
          cout << "Here are the comments of " << InFile << ":\n";
          // Read in each character until eof character is read.
          // Output it to screen.
         while (!InStream.eof()) {
                  //Read each character.
                 InStream.get(ch);    
                 if (!InStream.eof()) 
                 {
                          cout << ch;  //Write to screen
                 }
          }
          InStream.close();
}

Last edited by Ancient Dragon; Apr 26th, 2007 at 10:15 pm. Reason: corrected code tags to show line numbers

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Apr 26th, 2007

Re: Scan File for Comments

>>The code I have written so far works, but it prints the entire code

If it prints the entire code then it doesn't work, does it.

line 8: this is a c++ program, so replace the char array with std::string, which will allow you to enter a file name of any length up to the limit set by the operating system.

Line 16: if the file name contains spaces then that line will not work. Safer if you use getline().

lines 30-37: not a good way to detect eof. Don't read the file one character at a time -- that's too much work. Here's a simpler way to do this

c Syntax (Toggle Plain Text)
std::string line;
while( getline(InStream,line) )
{
      std::string::size_type pos = line.find("//");
      if(pos != std::string::npos)
      {
           std::string word = line.substr(pos);
           cout << word;
     }
}
std::string line;
while( getline(InStream,line) )
{
      std::string::size_type pos = line.find("//");
      if(pos != std::string::npos)
      {
           std::string word = line.substr(pos);
           cout << word;
     }
}

This doesn't solve the /**/ type comments but should work the // style commens. This was not compiled or tested, so use the above at your own risk.

Last edited by Ancient Dragon; Apr 26th, 2007 at 10:22 pm.

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Apr 27th, 2007

Re: Scan File for Comments

I've tried playing with it and it still hates me...lol!

(Toggle Plain Text)

 
#include
<iostream>
#include<fstream>
usingnamespace std;
int main()
         {
         std::string line;
         ifstream InStream;
         cout << "Enter input file name: " ;
         getLine();
         // Open file for input
         InStream.open(InFile, ios::in);
        // ensure file is opened successfully
        if(!InStream)
        {
           cout << "Error open file " << InFile << endl;
           return 1;
        }
        while( getline(InStream,line) )
        {
              std::string::size_type pos = line.find("//");
              if(pos != std::string::npos)
        {
              std::string word = line.substr(pos);
              cout << word;
}
}

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