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| -rw-r--r-- | c++.html.markdown | 39 |
1 files changed, 31 insertions, 8 deletions
diff --git a/c++.html.markdown b/c++.html.markdown index e50c33fa..517ce367 100644 --- a/c++.html.markdown +++ b/c++.html.markdown @@ -497,8 +497,10 @@ void printMessage() { cout << "Learn C++ in " << Y << " minutes!" << endl; } -// And you can explicitly specialize templates for more efficient code (most -// real-world uses of specialization are not as trivial as this): +// And you can explicitly specialize templates for more efficient code. Of +// course, most real-world uses of specialization are not as trivial as this. +// Note that you still need to declare the function (or class) as a template +// even if you explicitly specified all parameters. template<> void printMessage<10>() { cout << "Learn C++ faster in only 10 minutes!" << endl; @@ -667,7 +669,9 @@ void doSomethingWithAFile(const std::string& filename) // Fun stuff ///////////////////// -// Aspects of C++ that may be surprising to newcomers (and even some veterans): +// Aspects of C++ that may be surprising to newcomers (and even some veterans). +// This section is, unfortunately, wildly incomplete; C++ is one of the easiest +// languages with which to shoot yourself in the foot. // You can override private methods! class Foo { @@ -677,16 +681,35 @@ class FooSub : public Foo { virtual void bar(); // overrides Foo::bar! }; -// 0, false, NULL are all the same thing! + +// 0 == false == NULL (most of the time)! bool* pt = new bool; *pt = 0; // Sets the value points by 'pt' to false. -pt = 0; // Sets 'pt' to the null pointer. Yes both lines compile without warning. +pt = 0; // Sets 'pt' to the null pointer. Both lines compile without warnings. + +// nullptr is supposed to fix some of that issue: +int* pt2 = new int; +*pt2 = nullptr; // Doesn't compile +pt2 = nullptr; // Sets pt2 to null. + +// But somehow 'bool' type is an exception. +*pt = nullptr; // This still compiles, even though '*pt' is a bool! + + +// '=' != '=' != '='! +// Calls Foo::Foo(const Foo&) or some variant copy constructor. +Foo f2; +Foo f1 = f2; -// '=' != '=' -Foo f1 = f2; // Calls Foo::Foo(const Foo&) or some variant copy constructor. +// Calls Foo::Foo(const Foo&) or variant, but only copies the 'Foo' part of +// 'fooSub'. Any extra members of 'fooSub' are discarded. This lovely behavior +// is called "object slicing." +FooSub fooSub; +Foo f1 = fooSub; +// Calls Foo::operator=(Foo&) or variant. Foo f1; -f1 = f2; // Calls Foo::operator=(Foo&) or variant. +f1 = f2; ``` Futher Reading: |