Searching problem

[Jon182]

Hey guys, I am using the code below ot search for words in a text file and count them. I now would like to do something a little more advanced for example if a text file contains
"hello my name is kim" I want to be able to increment a variable everytime the words hello and my appear next to eachother, is there an easy way to do this?

Thanks.

char array [200];
ifstream file;

      while (file >> array)
	   {
			if(strstr(array,"test") != 0)
                        test++;
           }

[Narue]

Can you not use strstr to look for "hello my"? Or are you looking for any combination such as "my hello", hellomy", and so forth? In that case, the easiest way would be to use a regular expression, which C doesn't support as a standard library. You would need to write your own manually or use a third-party library. Alternatively, you can just hardcode a test for every possible combination. Your choice.

[Jon182]

Hi thanks for your quick reply I would hardcode each, but i'm not sure what you mean by a regular expression, what is that?

Thanks for your reply.

[Narue]

A regular expression is a way to search for patterns rather than exact matches.

http://en.wikipedia.org/wiki/Regular_expression

[Jon182]

Thanks, sorry i'm not very good at c++ how would I go about coding that? Could i use my array and the code I have posted above?

[Narue]

>Thanks, sorry i'm not very good at c++
This has nothing to do with C++ since you've shown that you can do a simple string search. At this point it's a problem solving issue. I personally don't think it's terribly difficult to do this:

if ( strstr ( array, "hello my" ) != NULL )
  ++test;
if ( strstr ( array, "hellomy" ) != NULL )
  ++test;
etc...

And since you're probably new to programming, it's unlikely that you'll have an easy time working with regular expressions.

[Jon182]

Thanks again for you help, I am just wondering how come its !=NULL rather than !=0?

The code also doesn't seem to be working for me is it because I am reading the file in one word at a time?

[Narue]

>I am just wondering how come its !=NULL rather than !=0?
Both are the same. NULL simply clarifies your intentions of using 0 in a pointer context. But if you use it, be sure to include a header that defines it. In C++ you'll probably want for NULL unless you use other C libraries.

>it because I am reading the file in one word at a time?
Yes. Use getline to read an entire line and it should work better.

[Bench]

> This has nothing to do with C++ since you've shown that you can do a simple string search. At this point it's a problem solving issue. I personally don't think it's terribly difficult to do this:

if ( strstr ( array, "hello my" ) != NULL )
  ++test;
if ( strstr ( array, "hellomy" ) != NULL )
  ++test;
etc...

And since you're probably new to programming, it's unlikely that you'll have an easy time working with regular expressions.

That is a "C" way of doing things, which is fine :)

Here is one method which is a bit more C++... (Yes OK, it is actually a bit more difficult than Narue's method)

int count(0);
    std::string::const_iterator iter(LineIn.begin());

    while(iter != LineIn.end() )
    {
        iter = std::search(LineIn.begin(), LineIn.end(), 
                           match.begin(), match.end() );
        if (iter != LineIn.end() )
        {
            ++count;
            ++iter;
            std::string s(iter, LineIn.end());
            LineIn=s;
        }
        
    }

LineIn is a std::string - using getline() from a file
match is a std::string - the string to match, eg, "hello my"

This method will not ignore whitespace, and will find multiple matches per string.
Although be careful to make sure that the strings are an exact match, ie, "Hello" != "hello" != "HELLO" != "HeLlO" .. etc.

the easy way around the mismatched strings is to change LineIn and match both 'tolower' (or 'toupper' - whichever floats your boat)