Programming Forums > Application Development > C++

dnathe4th · Oct 11th, 2004, 5:46 PM

a pointer refers to the location of memory which stores the value of a variable

that much I've gathered from online tutorials, but tell me this, why use pointers instead of the variables themselves?

Mjordan2nd · Oct 11th, 2004, 6:44 PM

Quote:

Speed: Imagine you want to write a progam that moves a lot of information around. In the conventional way, this would mean copying a lot of bytes from one part of the memory to another part. Take for example the sorting of an array with name.
(a pointer is just 4 bytes in Intel computers).

Flexibility: If, at the beginning of the program we do not know yet how many variables we need we would have to reserve space for all possible eventualities. If we want to write a program that calculates the first N prime numbers, with N given by the user, we would have to declare an array of maximum size to be sure that we can fit the users request in it. With this we would completely occupy the memory of the computer. Nothing else can run anymore. Much nicer would be if we could declare the array (the variables) dynamically so that we only use memory if we really need it. With pointers this is easily possible.

The pointers and the idea of dynamic creation of variables also lies at the basis of object-oriented programming, which is the type of programming of every modern computer language. Object oriented programming is outside the scope of this lecture, though.

http://w3.ualg.pt/~pjotr/pi/t14.html

Infinite Recursion · Oct 11th, 2004, 11:32 PM

Speed. But its not so much that speed is an issue anymore as modern computers are excessively fast.

Ravilj · Oct 12th, 2004, 2:00 AM

wait until you enter the world of object oriented programming and polymorphism, base classes, inheritance, virtual functions and base class pointers. Thats when pointers will show their uses.

Berto · Oct 12th, 2004, 3:18 AM

Pointers, linked Lists a must to learn but a headache all the same.

mici · Oct 12th, 2004, 7:36 PM

Quote:

Originally posted by dnathe4th@Oct 11 2004, 09:46 PM
a pointer refers to the location of memory which stores the value of a variable

that much I've gathered from online tutorials, but tell me this, why use pointers instead of the variables themselves?

It's as simple as this...
pointers let you direct functions to go somewhere instead of you bringing it to them... when it comes to simple variables it's all the same but when it comes to structs and similar....

imagine it like this:
is it easier to tell your woman where the kitchen is or to go and cook dinner...

dnathe4th · Oct 14th, 2004, 9:01 PM

Thanks guys, and by guys i mean MJordan

it makes a lot more sense now
Cheers

Oct 11th, 2004, 5:46 PM	#1
dnathe4th Programmer Join Date: Oct 2004 Posts: 32 Rep Power: 0	a pointer refers to the location of memory which stores the value of a variable that much I've gathered from online tutorials, but tell me this, why use pointers instead of the variables themselves? __________________ <CENTER><span style='font-size:17pt;line-height:100%'>My Homepage</span></CENTER>

Oct 11th, 2004, 11:32 PM	#3
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,473 Rep Power: 8	Speed. But its not so much that speed is an issue anymore as modern computers are excessively fast. __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."

Oct 12th, 2004, 2:00 AM	#4
Ravilj Programmer Join Date: Sep 2004 Location: JHB , South Africa Posts: 79 Rep Power: 5	wait until you enter the world of object oriented programming and polymorphism, base classes, inheritance, virtual functions and base class pointers. Thats when pointers will show their uses. __________________ Ravilj's OpenGL Terrain aka WinTerrain Last Updated: 17/01/2005!

Oct 12th, 2004, 3:18 AM	#5
Berto Programming Guru Join Date: Aug 2004 Posts: 1,022 Rep Power: 6	Pointers, linked Lists a must to learn but a headache all the same. __________________ "Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. THAT'S relativity." - Albert Einstein

Oct 14th, 2004, 9:01 PM	#7
dnathe4th Programmer Join Date: Oct 2004 Posts: 32 Rep Power: 0	Thanks guys, and by guys i mean MJordan it makes a lot more sense now Cheers __________________ <CENTER><span style='font-size:17pt;line-height:100%'>My Homepage</span></CENTER>

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