Are == and != operators compiler-generated? [closed] - c++

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Closed 9 years ago.
Do I need to provide == and/or != operators? I've read here: Why don't C++ compilers define operator== and operator!=? that I do but when I actually tried it (didn't provide them and tried to use them) the program compiled fine. So what's going on?
Using VS2010 if it matters.

These operators are defined for fundamental, language-defined types, not for your custom ones. So it will work for ints, for example. But won't for class foo; unless you provide them explicitly - compiler doesn't know how to compare your own defined types if you haven't told it how to do it.

Related

What does `::` do in C++ language? [closed]

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Closed 9 years ago.
I found a C++ file in PARSEC benchmark suite and saw some functions like this:
long Rng::rand()
{
return _rng->randInt();
}
what does the :: in the name of the function do here?
In C, :: is a syntax error unless it occurs inside a comment, a character literal or a string literal.
The :: can only appear in C++ code.
In C++ :: is the Scope resolution operator.
In this case it tells the compiler that it is a defintiion for rand() method which is a member function for Rng class/structure/union/namespace.

C++ class member seen as "not defined" [closed]

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Closed 9 years ago.
I have the following class:
class clsTree;
{
private:
vector<clsNode*>m_content;
m_RootNode *clsNode;
m_LastNode *clsNode;
public:
vector<clsNode*>Content;
wstring interpret(wstring uWord);
};
The compiler does not like my member declaration of clsNode at all.
The first error I get is "Member clsTree::clsNode is not a type name.".
I don't see where I went wrong.
Can somebody help, please?
You're not showing the definition of clsNode, neither whether you have a forward declaration for it, but I'm pretty sure this:
m_RootNode *clsNode;
m_LastNode *clsNode;
Should be rewritten this way:
clsNode* m_RootNode;
clsNode* m_LastNode;

Multilple template end tag [closed]

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Closed 9 years ago.
Ogre::any_cast<std::map<Rail>::iterator>
It takes Ogre::any_cast<std::map<Rail> and says too few arguments etc. How can I fix it (other than obvious typedef aliasing)?
The problem is that std::map takes at least two template arguments - the key type and the value type. Currently you have std::map<Rail>. What are you mapping from Rail to? For example, this would be okay if your iterators are for a std::map that maps from Rail to int (assuming Rail is not a deduced type):
Ogre::any_cast<std::map<Rail,int>::iterator>(some_any_object)

ISO C++ forbids comparison between pointer and integer [closed]

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Closed 10 years ago.
if((kulax>=schodki[i][0][0] && kulax<=schodki[i][1]][0]) && (kulay==schodki[i][2][0]+10))
spoczywa=true;
Hi guys, I have an array of integers which name is schodki and it is declared as int schodki[5][3][1] and the global variables : int kulax and int kulay.
What's wrong in the line of code which is above ?
EDIT : Of course. "i" is the value from current state of loop.
You have an extra ] in
kulax<=schodki[i][1]][0]
which probably screws up parsing and results in a confusing error message. The compiler probably sees it as
kulax<=schodki[i][1]
which is indeed an attempt to compare an integer to a pointer. Try to pay attention to your own code and make sure it is free from primitive syntax errors before asking questions here.
Other than that, there's nothing wrong with your code (assuming that the variables are really declared the way you say they are)].

Unicode support in Java SE7: missing classes for Unicode scripts? [closed]

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Closed 10 years ago.
I'm trying to capture Arabic text using the java regular expression \\p{IsArabic}, however the java compiler does not seem to recognize it, even though the documentation for java SE7 says it does.
I am pretty sure I'm using the correct compiler (JDK 1.7). In fact, the compiler is not recognizing any of the script classes, such as \\p{IsLatin} and \\p{IsGreek} ! Is anyone else having the same problem?