Please help me in parsing

Question

1.00/5 (1 vote)

See more:

I have an query

Suppose i have the following line in a text file

Hi i am xyxabc and i work for xyz

I want the output to be "and i work for"

I have the following code

C++

#include <fstream>
#include <string>
#include <iostream>
bool ParseLine(const std::string& line, std::string& key, std::string& value);
 
class Demo
{
public:
    typedef struct _Data 
    {
        std::string abc;
		
        
    } Data;
 
    Data data;
};
 
int main()
{
    std::ifstream ifs("Ca.txt");
    std::string line;
    std::string key;
    std::string value;
    Demo obj;
    while(!ifs.eof())
    {
        std::getline(ifs, line);
        if (ParseLine(line, key, value))
        {
            if (0 == key.compare("student"))
            {
                obj.data.name = value;
            }
         
			 else if (0 == key.compare("abc"))
            {
				obj.data.content = value;
            }
            else
            {
                std::cerr<<"Unknow key:" << key << std::endl;
            }
        }
    }
    return 0;
}
 
bool ParseLine(const std::string& line, std::string& key, std::string& value)
{
    bool flag = false;
    
if (line.find("//") != 0)
    {
        size_t pos = line.find(" ");
        if (pos != std::string::npos)
        {
            key = line.substr(0, pos);
			 size_t pos1 = line.find(";");
            value = line.substr(pos + 1, pos1);
            flag = true;
        }
    }
	
    return flag;
}

I want the output to be and i work for that is before xyz.

Posted 22-Feb-14 1:43am

Robert Clove

Add a Solution

Comments

CHill60 22-Feb-14 8:20am

Please do not repost the same question File ponter maintaince error please guide[^]

Robert Clove 22-Feb-14 8:24am

ok will take care of that any solution from ur side?

CHill60 22-Feb-14 8:36am

Haven't got 'C++' at this location - yet ... slow internet connection means I won't be getting it any time soon either :-( I'll have a look later

Robert Clove 22-Feb-14 9:06am

waiting for the solution

pharap@hotmail.com 23-Feb-14 9:03am

I'd like to point out that this isn't how parsers work, it's a common misconception that a parser takes a stream of text and turns it into something else. In actual fact, a parser takes a stream of things called tokens, which are made by a lexical analyser(aka scanner/tokeniser/lexer). The parser then emits a parse tree, which is then used to create usable output. Example: http://2.bp.blogspot.com/-HyH1_FXl6eQ/TzC60mQP9nI/AAAAAAAAAFY/g2B31KnChus/s1600/aa1.JPG

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

David O'Neil · Answer 1 · 2014-02-23T01:40:00

I won't go into much, but maybe this gets you started. Always try to start from the simplest version of the problem. I see something like this:

#include <string>
using namespace std;

int findSchoolEnd(const string & str) {
   size_t pos = str.find("xyxabc");
   if (pos == string::npos) return -1;
   return pos + string("xyxabc").length();
   }

int findStudentBegin(const string & str) {
   size_t pos = str.find("xyz");
   if (pos == string::npos) return -1;
   return pos;
   }

string getMiddleStuff(const string & str, size_t begin, size_t end) {
   if (begin == string::npos) return "";
   if (end == string::npos) return "";
   return str.substr(end, begin-end);
   }

int main() {
   string str = "Hi i am xyxabc and i work for xyz";
   size_t begin = findSchoolEnd(str);
   size_t end   = findStudentBegin(str);
   string result = getMiddleStuff(str, end, begin);
   }

Only begin working on the key comparisons after the core works, like the previous code does.

Good luck!