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Command Line (cin) Hiding & Counter Using C++

kuphryn · 2001-12-16T18:20:52

Hi. I was wondering how to: 1) hide what a user types, but still read the keys. I am working on a program that is involves password protection. I need a way to asks for the pass, but not display it openly just when logging onto any OS. A good example is logging onto linux. It asks for the password, but it does not display what the user enters. 2) code a counter that uses the clock as a seed. For example let say this is the code: cout << "testing"; cout << "1 "; ------------------3 second delay cout << "2 "; ------------------3 second delay cout << "3 "; In other word, is there a way to code some type of delay or counter? Thanks, Kuphryn

General and Gameplay Programming Programming

Started by kuphryn December 12, 2001 11:16 AM

16 comments, last by kuphryn 22 years, 4 months ago

Oluseyi

2,123

December 15, 2001 11:19 PM

quote:Original post by Oluseyi
while(((c = getch()) != ''q'') && (c != ''Q''))

This line has the unfortunate effect of making the program wait for the user to enter a key before being prompted for each string, which gets tiresome.

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Thanks to Kylotan for the idea!

kuphryn

210

Author

December 16, 2001 09:39 AM

Ahh. Thanks.

So there is not way to get getche() to work without namespace std right?

In your code, you have:

while(...c = getche()...)

and then

getline(cin, str)

What role does str play in the algorithm?

Kuphryn

Oluseyi

2,123

December 16, 2001 10:26 AM

quote:Original post by kuphryn
So there is not way to get getche() to work without namespace std right?

getch and getche are not part of the std namespace. The work with or without it. I included the std namespace because I''m lazy, and wont look up getline.

quote:What role does str play in the algorithm?

It is the destination of the string of input entered by the user. It is compared to see if it is "Q" or "q" (if it is, we exit) and displayed if it isn''t.

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Thanks to Kylotan for the idea!

TerranFury

142

December 16, 2001 11:45 AM

Your two questions are seperate and unrelated, right, kuphryn? All you want to do for the first one is to have someone enter a password but not show what is entered? If so, then here''s a simple way to do it:

  	char pw[256];    // Your string	char c;          // Stores an individual character	int i = 0;       // Stores the array index	for(;;)	{		c = getch();   //Wait for user to input a character                               //and set c equal to that character.		if(c == 13)			//If the user hit ENTER (13 = ENTER)		{			pw[i] = NULL;    //End the string with a NULL character			break;           //Exit loop		}		else		{			pw[i] = c;       //Add character to string                        i++;      		}	}

Oluseyi

2,123

December 16, 2001 12:16 PM

quote:Original post by TerranFury

    			pw[i] = NULL;    //End the string with a NULL character

  pw[i] = ''\0'';

I do not believe the two are equivalent.

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Thanks to Kylotan for the idea!

kuphryn

210

Author

December 16, 2001 01:19 PM

TerranFury,

Kick ass!!! Very elegant. It works great.

Here is a section of the code where I incorporated your technique with what I am trying to accomplish:

------------------------------------------------------{	bool veri = false;		string uKeyA, uKeyB, strOpt;	do	{		int tmpCh = 0;		uKsize = 0;				cout << "\nEnter a password (32 chars. max.): ";				while ((tmpCh = getch()) != 13)			uKeyA += tmpCh;			cin.clear();				uKsize = uKeyA.size();		if (uKsize > maxKeySIZE)		{			veri = false;uKeyA.erase(uKeyA.begin(), uKeyA.end());}					cout << "\n\nEnter that password one more time: ";				while ((tmpCh = getch()) != 13)			uKeyB += tmpCh;		cin.clear();				if (uKeyA == uKeyB)		{			veri = true;						for (int i = 0; i < uKsize; ++i)				key = uKeyA;		<br>		}<br><br>		else<br>		{<br>			veri = false;<br>			uKeyA.erase(uKeyA.begin(), uKeyA.end());<br>			uKeyB.erase(uKeyB.begin(), uKeyB.end());<br><br>			cout << "\n\nPassword does not match!  Try again."<br>————————————————————-<br> </pre>  <br><br>Note: I left some part of it out.<br><br>How did you determine integer 13 represents Enter or "\n?" Did you use:<br><br>cout << int("\n");<br><br>I am also trying to implement something like astrisks for each character like in windows.  I am confident I can get that done.  The code you post is simple, yet effectively.<br>—————-<br><br>Oluseyi:<br><br>Interesting.  I think he used NULL to end the string, not to indicate a new line.<br>—————-<br><br>Lastly, here is a simple character array:<br><br>char temp[5] = {'a','b','c','d');<br><br>It is a rule that the last space has to be NULL?  I think it is true if the program sends temp to cout.  However, what if temp is used only as a storage variable?  Is:<br><br>temp[4] = NULL;<br><br>required?<br><br>Kuphryn<br>   </i> <br><br>Edited by - kuphryn on December 16, 2001 2:21:06 PM

Kylotan

10,510

December 16, 2001 02:05 PM

Using ''NULL'' is awkward. It''s not defined as part of C++, so a compiler or header file that provides it could call it whatever it likes. I think MSVC defines it as 0L (zero as a long int) but I''ve seen it defined as (void*)0 before (zero as a pointer to void). Anyway, a string of characters should really be terminated with the zero character : ''\0''. Don''t rely on the compiler to make a conversion for you when you can do it explicitly - saves you on debugging time later.

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kuphryn

210

Author

December 16, 2001 06:20 PM

Message noted.

Deitel and Deitel C++ How to Program highlighted that it is recommend to use "0" or "''\0''" instead of NULL. I will convert from NULL to "0" or "''\0''" where applicable.

Thanks,
Kuphryn

Command Line (cin) Hiding & Counter Using C++

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