using while(cin)

**brane_sail** · 08-15-2003

help, i've spent many a desperate compile trying to tweak this code to get it to run but can't get it to work. The code looks like this:

Code:

char letter;

while(cin)
{
cin>>letter;
// do some stuff
}

the purpose of the code is to pull in whatever the user types one character at a time and when they hit enter to process it. The problem is that when I try it and i hit enter it just moves the cursor down one line and waits.

**funkydude9** · 08-15-2003

edit...

Your're never outputting anything, so it's waiting for input like you told it to do so.

Code:

char letter;

while(cin && letter != 'q')
{
     cout<<"Enter a character: ";
     cin>>letter;
     cout<<"You entered "<<letter<<endl;
}

**brane_sail** · 08-15-2003

I understand that, but is there a way to let the person type more then one character, say a sentence and then when they hit enter to let me process it one character at a time? I've thought of using the getch() function in conio.h but I've run into problem that if they make a mistake and need to hit backspace. I want to give them the freedom to type freely until they want to stop, at which time they press enter.

**JaWiB** · 08-15-2003

Code:

#include <iostream>
using namespace std;

int main(void)
{
char* myStr = new char;
cin>>myStr;
cout<<myStr;
}

And if you need to edit it character by character you can just loop through the array or something:

Code:

for (int i=0;myStr[i]!='\0';i++)
 //do something with myStr[i]

**7stud** · 08-15-2003

You can read in the whole sentence using cin.getline(), and then process the variable containing the sentence char by char.

**golfinguy4** · 08-15-2003

Originally posted by JaWiB

Code:

#include <iostream> using namespace std; int main(void) { char* myStr = new char; cin>>myStr; cout<<myStr; }

*cough*Free Memory*cough*

**JaWiB** · 08-15-2003

ERg always forget...

**Cat** · 08-15-2003

*cough* You also allocate only one byte for the buffer *cough*

**funkydude9** · 08-15-2003

*cough* Forgot to return 0 *cough*

**7stud** · 08-15-2003

*cough* Not to mention it won't work if the user enters multiple words. *cough*

**JaWiB** · 08-15-2003

*cough* Forgot to return 0 *cough*

Nope don't have to

*cough* Ok that's enough *cough*

**ZengJian** · 08-16-2003

The cin works the same way as a file stream. That is to say, the expression cin >> ??? would return true until you have pressed Ctrl-Z (EOF) and Enter.

**newbie_grg** · 08-16-2003

Code:

#include <iostream>
#include <cstdlib>
#include <conio.h>

using namespace std;

int main(std::string argv , int argc) {

string yourName = "doodlepoodle";

while( (getch())  && (getch() != 'q') ) //get input. input shouldn't be 'q' or else quits. 
 {
 cout << "hello "  << yourName << "\n"; // prints hello "yourName".
 } 												 // but dont forget to
 system("pause");			    				// press "enter" in 
 }		        									// the console 
	
//The problem with this code is however that it asks for input two times.
// i.e to quit i have to press 'q' as last one .

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