Overloading `++` and `--`, Condition States, and Strings

Overloading `++` and `--`

Prefix

Postfix

Overloading

In header (.h) file

class MyClass {
    ...
    const MyClass & operator++();  // prefix form
    MyClass operator++(int);       // postfix form
    ...
};

In source (.cpp) file

const MyClass & MyClass::operator++() { // prefix form
    // code to increment data members
    return *this;
}

MyClass MyClass::operator++(int) { // postfix form
    MyClass temp = *this;
    // code to increment data members
    return temp;
}

Condition States

States:

eof
good
bad
fail

Useful member functions (where `in` is a stream):

in.eof()
in.good()
in.bad()
in.fail()
in.clear()
in.setstate(state)

Note:

in.fail() is true if either ios::badbit or ios::failbit have been set
! has been overloaded for streams: !in is the same as in.fail()

Strings

C++ `string` Class

In string library ( #include <string> )

Overloaded support for relational operators ( == != > >= < <= = )

C++ strings are mutable:

Useful member functions:

Recommendation:

use string library
convert to and from C-style as needed but do all string operations using string library

C-Style Strings

C-style string = an array of characters ending in '\0'

Library support in cstring (need to #include <cstring>):

int    strlen( const char *str )

char * strcpy( char *LHS, char *RHS )

char * strcat( char *LHS, char *RHS )

int    strcmp( const char *LHS, const char *RHS )

Overloading ++ and --, Condition States, and Strings

Overloading ++ and --