CODEWITHSUNDEEP
c++
RubyKing
RubyKing

Reputation:

What is the proper way to use string::find to look for a word?

How would I look through a string for a word rather then each character in that word. I have my code here and it always seems to find everything that is .obj even if its o or b or j or "." I checked the docuementation here but was unable to find an answer. Here is my code:

 string &str = *it;

 if(it->find(".obj"))
 {
     cout << "Found .Obj" << endl;
 }

I also tried to use string::compare but that failed.

Upvotes: 0

Views: 87

Answers (1)

Trevor Powell
Trevor Powell

Reputation: 1174

find does search for the full text string that you pass as the function argument. What you're misunderstanding is the return value; find doesn't return true or false for whether or not it found the string you requested; it returns the index in the string where it found your requested substring, or std::string::npos if no match was found.

So for example:

std::string a = "foobar.obj";
std::string b = "baz.obj";
std::string c = "qux";
std::string d = ".obj";

a.find(".obj") == 6
b.find(".obj") == 3
c.find(".obj") == std::string::npos // not found
d.find(".obj") == 0

When interpreted as a boolean value, any integer other than 0 is treated as "true" -- even the "not found" std::string::npos value. Which is, I think, what has you confused.

So in your "if" statement, then, instead of:

if (it->find(".obj"))

You want to be testing:

if (it->find(".obj") != std::string::npos)

Upvotes: 8

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