Ordering C++ strings

I tried using the strcmp function on a C++ string class and the compiler complains. I know C++ string is a class and C string character array but do they not still have the same features that strcmp can operate on?

Secondly. I tried alphabetically ordering a vast number of words using the correct way through string::compare. Although they look ordered at first, after close inspection half of the words starting from the second letter onwards are unordered slightly like:

ABC
CIF
CIB
CI
CHUTS
CIRCLIP
DOK

I used the standard compare lines:
str1.compare(str2 < 0) with no other parameters.
So why does it do this?

Thirdly and finally, what does the simple statement string1 < string2 do?

Quote:

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Originally Posted by Vespasian

I tried using the strcmp function on a C++ string class and the compiler complains. I know C++ string is a class and C string character array but do they not still have the same features that strcmp can operate on?

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strcmp is oblivious to what a std::string is (it has no overload that takes a std::string), and no implicit conversion from std::string -> const char* exists, therefore it does not work. There is no need to use strcmp with std::string.

Quote:

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Secondly. I tried alphabetically ordering a vast number of words using the correct way through string::compare. Although they look ordered at first, after close inspection half of the words starting from the second letter onwards are unordered slightly like:

ABC
CIF
CIB
CI
CHUTS
CIRCLIP
DOK

I used the standard compare lines:
str1.compare(str2 < 0) with no other parameters.
So why does it do this?

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I am going to take it you did...
str1.compare(str2) < 0
...and if that is the case, you need to post an example of your code that demonstrates the problem.
Otherwise, you have a bug (though I don't think it should compile).

Quote:

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Thirdly and finally, what does the simple statement string1 < string2 do?

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The same thing as str1.compare(str2) < 0.

string::compare is really for situations when you want to compare part of a string with another string.

Quote:

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Originally Posted by Elysia

strcmp is oblivious to what a std::string is (it has no overload that takes a std::string), and no implicit conversion from std::string -> const char* exists, therefore it does not work. There is no need to use strcmp with std::string.


I am going to take it you did...
str1.compare(str2) < 0
...and if that is the case, you need to post an example of your code that demonstrates the problem.
Otherwise, you have a bug (though I don't think it should compile).


The same thing as str1.compare(str2) < 0.

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Here it is. Its a function that, depending on whether the word is less than or greater than, assigns the read node to the left leaf or right leaf of a binary tree node.

Code:

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struct masternode* insert(struct masternode* node, string token) {
    if (node == NULL) {
        return(NewNode(token));
        }
    else {
        if (token.compare(node->token) < 0)
            node->left = insert(node->left, token);
        else if (token.compare(node->token) > 0)
            node->right = insert(node->right, token);
        else
            (node->count)++;
        return(node);
        }
}

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