Having trouble with char*

Alright, so I know that you can use char pointers to store strings, and
I'm trying to make a very simple program to see how it all works that
will have the user enter 5 characters, then the computer will show
those five characters back to the user. So far I have:

#include <iostream.h>

int main()
{
char* buffer = " "; //Five spaces
char in;
char out;

while(in = *buffer++)
{
cin >> in;
}

while(out = *buffer++)
{
cout << out;
}

return 0;
}

This program works how it is supposed to until it gets to the
outputing; nothing happens. It gets the five characters, then ends.
Please help me make this work, and if possible I want it to be based
off of using the char*, and not an array or just five char variables.
Thank you!

re: Having trouble with char*

Ian Arnold wrote:[color=blue]
> while(in = *buffer++)
> {
> cin >> in;
> }[/color]

in is modified by cin which ends when enter is pressed (or equivalent).
[color=blue]
>
> while(out = *buffer++)
> {
> cout << out;
> }
>
> return 0;
> }[/color]

Seriously, what do you want to do?

This program doesn't read 5 character, and in C++ you cannot read X
characters and stop the input, this would be platform dependent (DOS is
different from linux)... you can read strings, int, whatever, but you
can't interrupt an input.

re: Having trouble with char*

On Sat, 02 Jul 2005 12:12:57 -0700, Ian Arnold wrote:
[color=blue]
> Alright, so I know that you can use char pointers to store strings, and
> I'm trying to make a very simple program to see how it all works that
> will have the user enter 5 characters, then the computer will show
> those five characters back to the user. So far I have:
>
> #include <iostream.h>
>
> int main()
> {
> char* buffer = " "; //Five spaces
> char in;
> char out;
>
> while(in = *buffer++)
> {
> cin >> in;
> }
>
> while(out = *buffer++)
> {
> cout << out;
> }
>
> return 0;
> }
>
> This program works how it is supposed to until it gets to the
> outputing; nothing happens. It gets the five characters, then ends.
> Please help me make this work, and if possible I want it to be based
> off of using the char*, and not an array or just five char variables.
> Thank you![/color]

What book from hell are you reading?

#include <iostream>
#include <cstdlib>

using namespace std;

int main()
{
char buffer[5], *c=buffer; // can use the same char* for both I/O

while(c<buffer+5)
cin >> *(c++); // parantheses not necessary, but good for beginners.

c=buffer;
while(c<buffer+5)
cout << *c++;
cout << endl;

return 0;
}

re: Having trouble with char*

Ian Arnold wrote:
[color=blue]
> Alright, so I know that you can use char pointers to store strings,[/color]

You don't use pointers to store strings. You use arrays for storing them and
the pointers to point to the start or any other character of such an array.
char* is _not_ a string type. It's a pointer to a char and nothing else.
[color=blue]
> and I'm trying to make a very simple program to see how it all works that
> will have the user enter 5 characters, then the computer will show
> those five characters back to the user. So far I have:
>
> #include <iostream.h>[/color]

This is an ancient non-standard header. Instead, use:

#include <iostream>

[color=blue]
> int main()
> {
> char* buffer = " "; //Five spaces[/color]

Five spaces (plus a '\0' character) that can _not_ be modified. String
literals are constant, and your pointer points to one.
[color=blue]
> char in;
> char out;
>
> while(in = *buffer++)[/color]

Ok, here, you copy the next character from the string into 'in'.
[color=blue]
> {
> cin >> in;[/color]

Here, you overwrite 'in' again. Then you do nothing with it.
[color=blue]
> }
>
> while(out = *buffer++)
> {
> cout << out;
> }
>
> return 0;
> }
>
> This program works how it is supposed to until it gets to the
> outputing; nothing happens.[/color]

That's not quite right. The five spaces that are still in the string literal
are printed.
[color=blue]
> It gets the five characters, then ends.
> Please help me make this work, and if possible I want it to be based
> off of using the char*, and not an array or just five char variables.[/color]

I suggest you use std::string instead.