Using String::Find function

Question

0.00/5 (No votes)

See more:

I'm trying to find a string within a string and its not returning anything.....

C++

if (client.SendHttpRequest())
    {
        wstring httpResponseHeader = client.GetHttpResponseHeader();
        string str ("wstring httpResponseHeader");
		string str2 ("Content=");
		size_t found;
		found=str.find(str2);
		printf("\n%s\n\n",found);
		//wstring httpResponse = client.GetHttpResponse();
        wprintf(L"HTTP Response Header:\n%s\n\n", httpResponseHeader.c_str());
        
		//wprintf(L"HTTP Response:\n%s\n\n", httpResponse.c_str());
    }

Posted 24-Aug-11 5:09am

Member 7766180

Add a Solution

2 solutions

Solution 2

You should deal with another hobby or learning the basics of programming. Buy you a good book or check out the tons of examples in the WorldWideWeb. Why you are starting with http protocol? Nobody will help you with your stupid repeating questions.
Regards.

Posted 24-Aug-11 5:40am

mbue

Comments

Stefan_Lang 24-Aug-11 11:45am

While you are probably right in your assessment of the programming skills of the poster, there is no reason to be harsh about it. Everybody has to start somewhere, so if you have a good link to provide, post it, or else there is no point in posting a 'solution'.

mbue 24-Aug-11 11:52am

He should start with a simple exercise. And should not spam many times a day the same question.
btw: this is a solution: "By you a book", "Check out simple examples", "Learn the basics", "Use the web to get examples"!
Regards.

Member 7766180 24-Aug-11 12:49pm

That was very rude on your part. I'm trying to learn this and there is no reason to be abusive. Besides you obviously don't think that I have been searching? I use codeproject as a last resource after many days of searching, and my question is hardly spam! It's a legitamite problem I am having. What is your solution?

Emilio Garavaglia 24-Aug-11 13:48pm

The problem is the way you are approaching the problem is wrong. There are many solution, but all of them presume to completely rewrite your code (that look as a random messing-up of not understood concepts). A more proper approach is: you want to process HTML, but this requires understanding of networking, socket programming and string manipulation. Ok. Now forgot HTML for a while, and start studying those concept one by one with example proper of their own domains. Study how C++ handle and manage stings. Study how C++ handles I/O. And you will discover you have to understand operator overloading and templates. Stop a while, and start from them. Then pass to the C++ standard library: strings, I/O, containers and iteration. Then study the HTML specs. Only at that point start working on it. Whatever other help is misleading, and will give you even more confusion. Ha... also understand that C++ is not C. Whether it can call old C functions, there are better and more robust way to do certain things. Forget printf: C++ I/O is different.

Member 7766180 24-Aug-11 14:07pm

Thank ypu for your sound advice. Your right, I need to get rid of printf and use c++ I/O. The whole thing is I am getting what I want using WSA but I have have this last problem of getting Content-Type from an http header where I can actually refrence it to run logic from it.

mbue 24-Aug-11 13:55pm

Most people having questions are telling us what they have done and what happens with there code. you are splashing a piece of code and asking whats wrong about that.
Have you ever used the debugger and debug messages like trace? in debugger you can examine the incoming values. so you can see whats wrong with your code.

Member 7766180 24-Aug-11 14:09pm

Of course I'm using debugger. I just have the difficult problem of extracting Content-Type from a http header so that I can run logic.

mbue 24-Aug-11 14:31pm

congratulations. next step is to trace incoming values and the result of your operation (post it here). so we can see whats going on in your black box.

Stefan_Lang 25-Aug-11 4:18am

The problem is that for someone just starting to learn programming by himself, 'Buy a book' is not a very useful advice. He started out to 'learn by doing', so what he needs is advice on the kind of algorithms and techniques he's most interested in, and he's not likely to find that by buying a book - not very quickly anyway.

Not saying that 'buying a book' is bad advice in general, just that for someone who decided to teach himself it's likely to be more frustrating than helpful. What keeps people interested in learning is seeing results, not spending weeks to find and read books, that just turns them off. Therefore I prefer to offer practical advice that directly refers to the things that person wants to achieve so he can reach his goals and merit the results. It doesn't matter the way he goes about it is completely out of whack; of course it is, how should he know better. What matters he's willing to spend time and effort to learn something.

That said I agree that it would have been better to start with something simpler. Unfortunately though, for a beginner it's quite hard to judge how hard a given problem can be. I know some of my first programs solved problems I didn't think could be solved that easily, whereas other programs took orders of magnitude longer than I ever expected. It's hard to judge these things, and even harder when you have no experience to build on.

Member 7766180 25-Aug-11 13:36pm

Stefan, That is a wonderful well thought out answer! It should be posted on the home page of codeproject! Really, you hit the nail squarely on the head. In that spirit I think that it's important that people help each other, after all, the more people that know and use the c++ language keeps it alive and viable. And keeps those employment opportunities coming in for everyone. Once again thank you for your deep insight.

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)

Stefan_Lang · Accepted Answer · 2011-08-24T05:36:00

What do you expect to find? The string your searching in is "wstring httpResponseHeader" and you're searching for "Content=" which is not part of that string. Then you store the result of the find member function in the variable found. Note that this value is a position value, and in this case will return the predefioned constant string::npos (which by the way is not equal to 0).

The reason you don't see any useful result from your printf statement however is entirely different: you provide a format string that expects a variable of type string (format specifier %s), but you provide a value of type size_t, which of course doesn't fit. Unfortunately printf does not (and in fact can not) do any type check, so it tries to convert string::npos into a char pointer, which of course results in something unexpected. Ahhh, the wonders of type-unsafe C functions...

If you want some type-safe output, use iostrem, like this:

C++

#include <iostream>
//...
   std::cout << std::endl << "find result: " << found << std::endl;

Note: std::endl is the equivalent of a line break; the main difference to '\n' is that it is guaranteed to work on any operating system, inlcuding those that require an additional '\r' (carriage return).

P.S.: check this out: http://www.cplusplus.com/reference/string/string/find/[^]