what is : operator ?

what is : operator ? what it does ? i know about scope resolution operator. it is written as :: but what is : operator ?
can anybody explain plz. i dont know the name of this operator.

if anybody give very simple example, will be glad.

probabily these are written inside a class.

thanks

There is no such thing as operator :

However, there is the ternary operator, which uses ? and :

Code:

---

#include <iostream>

int main()
{
    bool expression = true;
    char result = expression ? 't' : 'f';
    std::cout << result << std::endl;

    expression = false;
    result = expression ? 't' : 'f';
    std::cout << result << std::endl;

    int var = 10;
    result = var == 10 ? 't' : 'f';
    std::cout << result << std::endl;

    var = 20;
    result = var == 10 ? 't' : 'f';
    std::cout << result << std::endl;
}

---

If the expression evaluates to true, then the first value is returned, otherwise the second value is returned. I think you can overload the ternary operator for a class, but I think it is rarely a good idea.

? : is the tertiary operator.


a < b ? a : b;

the above line is the equivalent of

if(a < b)
return a;
else
return b;

In more general terms it says if the conditional statement before the ? operator is true then return the variable before the : operator, else return the variable after the : operator.

: is also used as in initialization lists for classes, and maybe more. ? may be used for other purposes as well. But when used together, that's what it does.

>I think you can overload the ternary operator for a class
No, the ternary conditional operator is one of the operators that cannot be overloaded.

i am well aware of the ternary operator in C . i have seen these to use for the class constructor.i am sorry, i dont have the example right now . but is there any other way to use this operator in a class ? or any other application except this ?

>i have seen these to use for the class constructor.
You mean something like this?

Code:

---

myClass::myClass ( int a, int b, int c )
  : mya ( a )
  , myb ( b )
  , myc ( c )
{}

---

The colon simply says that what follows will be an initialization list followed by the constructor body instead of just the constructor body. The ? operator is only used in conjunction with : as the conditional operator, but : is used elsewhere (bit fields, inheritance, labels).

exactly i was talking about that.

Quote:

---

The colon simply says that what follows will be an initialization list followed by the constructor

---

not clear.

what is the equivalent code of that ?
your brackets are not properly written probabily

>what is the equivalent code of that ?
In this case:

Code:

---

myClass::myClass ( int a, int b, int c )
{
  mya = a;
  myb = b;
  myc = c;
}

---

>your brackets are not properly written probabily
...

yes,latter one i know and that is very simple . i also read about initialization list from my book.

i wonder, how many ways a simple thing can be made complicated !! there are many syntaxes for the same thing!!

anyway, its fine....ok

thanks

>how many ways a simple thing can be made complicated !!
You really don't want to know. :)

>there are many syntaxes for the same thing!!
Well, when it comes to initialization lists, there is a purpose. Create a class with a const or reference member and see how far you get trying to initialize it in the constructor body.

You all forgot about when using switches

Code:

---

switch(variable) {
    case something:
          statement;
          break;
etc.

---

>You all forgot about when using switches
>>but : is used elsewhere (bit fields, inheritance, labels)
;)

You caught me prelude, I forgot about labels and bitfields, haven't done too much with inheritence yet, I still am learning c++. I guess the : operator is the misc. operator. Do all know all operator. :)