cout technically isn't a part of C++

Shadow12345 · 10-01-2002

If the only think u know how to do is 'cout << ' with text in C++, then all you really know how to do is use the bitshift operator because cout isn't a part of the C++ programming language, it's just an object of output stream class declare in iostream...right? Even if something is in the stl that doesn't make it an intrinsic part of the C++ programming language, intrinsic parts of the language are really only the keywords, templates, pointers, references, stuff like that. Right? Or should I just be slapped?

EDIT:
You would also know how to include header files and use main() if you could do 'cout <<'...obviously

EDIT1:
Whoa, the output stream has a lot of members...this is sweet

**lightatdawn** · 10-01-2002

>>then all you really know how to do is use the bitshift operator

Except thats not bit shifting. That is the bit shifting operator, true, but thats not its function in this case. cout overloads those operators for its own use.

**Aran** · 10-01-2002

uh...

operator>> in that context is called the insertion operator and operator>> in the cin context is known as the extraction operator (i may have flipped those around because i haven't called them by their names in such a long time).

And saying cout isn't part of C++ is like saying printf isnot part of C.

**Sang-drax** · 10-01-2002

The function of cout is specified in the ANSI/ISO standard. Thus, it is part of the C++ language.

Shadow12345 · 10-01-2002

works for me

then how do you use the bitshift operator

**Prelude** · 10-01-2002

>then how do you use the bitshift operator
Very carefully.

-Prelude

Shadow12345 · 10-02-2002

but...what exactly does it do? I've seen it used before other than with cout, but I didn't know what its purpose was. Why do you need to 'shift bits', why can't we just leave the poor bits alone?

**BMJ** · 10-02-2002

Bit shifting is a good way to do some very fast math, that is... if you're good with base-2/8/16 math

**BMJ** · 10-02-2002

It can also be used for something like this:

Code:

#include <iostream> 

int main()
{
    int counter, num;

    std::cout << "Enter a number: ";
    std::cin >> num;

    std::cout << num << " is binary: ";

    for (counter=8; counter>=0; counter--)
        std::cout << ((num >> counter) & 1);
    std::cout << std::endl;

    return 0;
}

If you did not know what the shift right operator was, then this would probably confuse you

**DougDbug** · 10-02-2002

Bits are the individual 1's and 0's that the computer uses to store information.

Binary means base 2.

Bit-shifting is a binary operation.

So, if I have 00000111 binary (Equal to 7 decimal) and I bit-shift one position, I will have 00001110 binary (Equal to 14 decimal).

Every shift-left multiplies the number by two. Every shift-right divides by two. I think that's why BMJ says "fast easy math".

This binary stuff is used by us engineers where a single bit is set (to one) or cleared (to zero) by a switch or something.

If you want to learn about this stuff you'd need to look into "binary math" and boolian logic". Since it's easy to convert between hexadecimal (base 16) and binary, and it's easier (for us humans) to read and write hex, a lot of this stuff is coded in hex.

**Nick** · 10-02-2002

http://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_2.html

**lightatdawn** · 10-02-2002

>then how do you use the bitshift operator
Very carefully.

lol. How so? Unless of course you mean the obvious mistake of being an idiot and accidentally replacing 'x / 2' with 'x >> 2' because, maybe its 4 am and you've been coding for 19 hours straight... no, honest, I've never done that.

>>why can't we just leave the poor bits alone?

They're just asking for it.

Other uses include something like this which I use on a fairly regular basis:

//These #defines retrieve R,G,B, or A values from a DWORD (D3DCOLOR)
#define RetrieveB(rgb) ((BYTE)(rgb))
#define RetrieveG(rgb) ((BYTE)(((WORD)(rgb)) >> 8))
#define RetrieveR(rgb) ((BYTE)((rgb)>>16))
#define RetrieveA(rgb) ((BYTE)((rgb)>>24))

(And nobody whine about using macros instead of inline functions. Theres nothing wrong with macros if you're careful. The only problems lie in carelessness.)

**Eibro** · 10-02-2002

Why are you using macros? You should be using inline functions

**lightatdawn** · 10-02-2002

*grrr* I should have expected that.

**SilentStrike** · 10-02-2002

"Theres nothing wrong with macros if you're careful."

But rather than macros that look like macros (alerting reader not to do stuff like side effects in the arguments) they look like ordinary functions. Given, everyone's style is different, but I'd say caps for macros is really widespread and good practice.

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