Programming Forums > Application Development > C++

b1g4L · Feb 15th, 2006, 11:14 PM

I need a way to get next token after I input a list of chars using spaces to separate them.

For instance, if I input a string like this:

(Toggle Plain Text)

string tempInput;
cin >> tempInput;

and the user types in (without the quotes) "a b c d e f g h"
How can I get each char separately? I need to do some processing on each char.

jaeusm · Feb 16th, 2006, 12:36 AM

(Toggle Plain Text)

char c;
cin.get(c);

This does not ignore spaces, however.

You could also read in the whole line and parse the string.

xpy · Feb 16th, 2006, 8:00 AM

use this....

char c[]="";
cin>>c;

now you can either use it like this:
cout<<c; //prints the whole word
or like this:
cout<<c[3]; //prints the fouth letter of the word

you dont need know the length of the word c++ sets automaticaly the last letter as char(0)...

DaWei · Feb 16th, 2006, 9:49 AM

That's shitty advice. Please don't do that. It will not help, it will hinder. 'char c [] = "";' sets aside an array of char of only one byte, the terminator. Attempting to put any input into it will overflow and cause any number of problems, most likely including a segmentation fault.

b1g4L · Feb 16th, 2006, 9:59 AM

Quote:

Originally Posted by DaWei

That's shitty advice. Please don't do that. It will not help, it will hinder. 'char c [] = "";' sets aside an array of char of only one byte, the terminator. Attempting to put any input into it will overflow and cause any number of problems, most likely including a segmentation fault.

Any advice on how to input a char at a time of a string?

DaWei · Feb 16th, 2006, 10:36 AM

Sure. If you declare a single character,

(Toggle Plain Text)

   char c;
   cin >> c;

cin will only go for one character, instead of a possible array of char, and not overflow. Of course you have to dispose of 'c' somewhere before you fill it again (as with a loop). There are several methods associated with cin that allow you to read in different types, C++ strings, char arrays with a limit specified, etc. The extraction operator (>>) is not the only method associated with cin. I recommend you consult your documentation regarding cin and istreams.

b1g4L · Feb 16th, 2006, 1:05 PM

Ok this will input a string until whitespace is ecountered or end of string. I need to be able to ignore whitespace.....any ideas?

(Toggle Plain Text)

#include <iostream>
using namespace std;

int main ()
{
    string tempInput;
        
    cout << ("Enter a string") << endl;
    cin >> tempInput;
    cout << ("String entered was: ") + tempInput << endl;
    cout << ("Chars in order entered") << endl;
    for (int i = 0; i < tempInput.length(); i++)
    {
        cout << tempInput[i] << endl;
    }
    
    return 0;
}

DaWei · Feb 16th, 2006, 1:16 PM

Read an entire line. That's why I suggested other cin methods. "getline" is one. It allows you to read an entire line (you specify the terminator, if you like), or up to some maximum number of characters you specify (to avoid overflow), whichever comes first. Whether you use the extraction operator or another method, don't forget to test for failure. Your user can easily cause it. Failing to check is amateurish at best and dereliction once you know you need to.

ivan · Feb 16th, 2006, 2:30 PM

If all letters will be separate by a white space you could read the entire line and than parse the line with strtok() function. I will leave you to read the documentation about the function.

InfoGeek · Feb 16th, 2006, 6:58 PM

strtok works with char arrays only. See this thread for a C++ way: http://www.programmingforums.org/for...ead.php?t=5037

Feb 15th, 2006, 11:14 PM	#1
b1g4L Programmer Join Date: Dec 2005 Location: SC Posts: 38 Rep Power: 0	cin to getnext I need a way to get next token after I input a list of chars using spaces to separate them. For instance, if I input a string like this: (Toggle Plain Text) string tempInput; cin >> tempInput; string tempInput; cin >> tempInput; and the user types in (without the quotes) "a b c d e f g h" How can I get each char separately? I need to do some processing on each char.

Feb 16th, 2006, 12:36 AM	#2
jaeusm Programmer Join Date: Feb 2006 Location: Columbus, OH Posts: 84 Rep Power: 3	(Toggle Plain Text) char c; cin.get(c); char c; cin.get(c); This does not ignore spaces, however. You could also read in the whole line and parse the string.

Feb 16th, 2006, 8:00 AM	#3
xpy Newbie Join Date: Feb 2006 Posts: 1 Rep Power: 0	this will help you... use this.... char c[]=""; cin>>c; now you can either use it like this: cout<<c; //prints the whole word or like this: cout<<c[3]; //prints the fouth letter of the word you dont need know the length of the word c++ sets automaticaly the last letter as char(0)...

Feb 16th, 2006, 9:49 AM	#4
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	That's shitty advice. Please don't do that. It will not help, it will hinder. 'char c [] = "";' sets aside an array of char of only one byte, the terminator. Attempting to put any input into it will overflow and cause any number of problems, most likely including a segmentation fault. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Feb 16th, 2006, 10:36 AM	#6
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Sure. If you declare a single character, (Toggle Plain Text) char c; cin >> c; char c; cin >> c; cin will only go for one character, instead of a possible array of char, and not overflow. Of course you have to dispose of 'c' somewhere before you fill it again (as with a loop). There are several methods associated with cin that allow you to read in different types, C++ strings, char arrays with a limit specified, etc. The extraction operator (>>) is not the only method associated with cin. I recommend you consult your documentation regarding cin and istreams. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Feb 16th, 2006, 1:05 PM	#7
b1g4L Programmer Join Date: Dec 2005 Location: SC Posts: 38 Rep Power: 0	Ok this will input a string until whitespace is ecountered or end of string. I need to be able to ignore whitespace.....any ideas? (Toggle Plain Text) #include <iostream> using namespace std; int main () { string tempInput; cout << ("Enter a string") << endl; cin >> tempInput; cout << ("String entered was: ") + tempInput << endl; cout << ("Chars in order entered") << endl; for (int i = 0; i < tempInput.length(); i++) { cout << tempInput[i] << endl; } return 0; } #include <iostream> using namespace std; int main () { string tempInput; cout << ("Enter a string") << endl; cin >> tempInput; cout << ("String entered was: ") + tempInput << endl; cout << ("Chars in order entered") << endl; for (int i = 0; i < tempInput.length(); i++) { cout << tempInput[i] << endl; } return 0; }

Feb 16th, 2006, 1:16 PM	#8
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	Read an entire line. That's why I suggested other cin methods. "getline" is one. It allows you to read an entire line (you specify the terminator, if you like), or up to some maximum number of characters you specify (to avoid overflow), whichever comes first. Whether you use the extraction operator or another method, don't forget to test for failure. Your user can easily cause it. Failing to check is amateurish at best and dereliction once you know you need to. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

Feb 16th, 2006, 2:30 PM	#9
ivan Professional Programmer Join Date: Sep 2005 Location: serbia & montenegro Posts: 484 Rep Power: 4	If all letters will be separate by a white space you could read the entire line and than parse the line with strtok() function. I will leave you to read the documentation about the function.

Feb 16th, 2006, 6:58 PM	#10
InfoGeek Professional Programmer Join Date: Jun 2005 Location: India, The great. Posts: 435 Rep Power: 4	strtok works with char arrays only. See this thread for a C++ way: http://www.programmingforums.org/for...ead.php?t=5037 __________________ PFO - My daily dose of technology.

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cin to getnext