Thread: 2 simple question

hi all, i was browsing archieves ....i see forum memebers are using the follwing syntax

1. unsigned x // is it legal ?

i have seen only unsigned int x or unsigned char c etc. but some memebers are writing simply unsigned x. no data type !!!!. still the program works. question is how the program know what data type it is ? is it a standard ?


2. sizeof x // is it legal ?


i know only sizeof(x) // paranthesis . sizeof is a operator. how the above syntax works ?


3. returning inside a function.


func(param1,param2)
{

if(condition) // code

return ; // is it legal ? look ,what to be returned is not specified

else

return;


}


generally we write return some_variable or return some_number.

but in the above syntax what will be returned ? nothing is specified at all !!


thanks


all the above syntax works. can anybody give some comment on this.

1. unsigned means "unsigned int".

2. I am unfamiliar with sizeof x without parentheses. hmmm.

3. You can only return nothing if the function is supposed to return nothing. ie:

Code:

int func()
{
return;
}

Is invalid.

Code:

void func()
{
return;
}

Is valid.

You can only return nothing if the function is supposed to return nothing. ie:

......but if you are writnig a func it is bound to return something. this is a function rule.

You're thinking Visual Basic. No, in C++, you don't have to return a value.

>1. unsigned x // is it legal ?
Yes. An unadorned "unsigned" is taken to mean unsigned int. Though if you need an unsigned short or long then you must say so explicitly.

>2. sizeof x // is it legal ?
Yes, provided that x is not a type name. If the operand to sizeof is a "thing" then you can omit the parentheses, but if the operand is a type you must use them:

Code:

int x;

sizeof ( x ); // Legal
sizeof x; // Also legal
sizeof ( int ); // Legal
sizeof int; // Not legal

>return ; // is it legal ?
Yes, provided that the function was declared to return void. It is equivalent to falling off the end of the function. The two following functions perform the same way:

Code:

void foo()
{
  return;
}

void bar()
{
}

>but if you are writnig a func it is bound to return something. this is a function rule.
C++ makes no distinction between functions and subroutines. A C++ function performs both jobs:

Code:

void subroutine ( int x )
{
  cout<< x <<endl;
}

int function ( int x )
{
  cout<< x <<endl;
  return x;
}