C++ language related

• Method Overloading vs Method Overriding?

  (from http://www.codeproject.com/useritems/Overload_Vs_Overriding.asp)
  • Method Overloading:
    Method overloading means having two or more methods with the same name but different signatures in the same scope. These two methods may exist in the same class or another one in base class and another in derived class.
  • Method Overriding:
    Method overriding means having a different implementation of the same method in the inherited class. These two methods would have the same signature, but different implementation. One of these would exist in the base class and another in the derived class. These cannot exist in the same class.

• Const

  • const_iterator: iterates over consts
  • const_cast: casts to and from a const

• Switch-case

  • switch-case: just continues after a matching case and ignores other case statements if no break is added!! So other cases don't act as "if" subsitutes or so...

• Octal numbers

  A number beginning with "0", like "010" is interpreted in C++ as an octal number. However, numbers like "08" and "09" were not rejected by old C++ compiler, which gave rise to very strange bugs... Nowadays, compilers don't accept these values anymore.

• isinf / isnan

  • from http://www.thescripts.com/forum/thread537713.html isnan is C99 function, while VC++ is not C99 compliant yet, so use
    

    #define isnan(x) ((x) != (x))

    instead.
  • Solutions: check the representation according to the IEEE 754 standard using bitwise operations
  • isnan: if x = nan, then x != x; if x = inf, then x == x

• Default structs as method arguments

  • Declare in the object with that method a static const member with the corresponding struct and in case of a struct with just two int's, initialize that static const struct as follows:
    static const MyStruct stDefValue = { 100, 100 };
    (from http://www.codeproject.com/cpp/Default_Struct_Parameter.asp)

• Headers

  • g++ finds its includes in /usr/include/c++/[C++-Version-Nr], except for system specific values, like the ones in float.h. These files are in /usr/lib/gcc-lib/

• STL

  • When composing a string using a stringstream (#include < sstream > ) in following code:   

    void function(char* pChar); int i = 1; stringstream ss; ss << "text" << i << ".txt"; char* oldCString = const_cast< char * >( ss.str().c_str() ); function( oldCString );

    
    produces an error: ss.str() copies data from ss into a temporary string which does not exist in the scope of function. string.c_str() however points to data inside string, so function gets a pointer to some memory that has been freed already. So it would be better to implement as follows:
      

    void function(char* pChar); int i = 1; stringstream ss; ss << "text" << i << ".txt"; string stringName = ss.str(); char* oldCString = const_cast< char * >( stringName.c_str() ); function( oldCString );

    because the result of ss.str() is copied in a string which goes out of scope after function was called.