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problems with type q to quit

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problems with type q to quit

 
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  #1
Mar 11th, 2009
This subroutine is very basic, however I am struggling.

When the user types q (or Q) into the input when asked for the vendor name, the program should return false... However, this function is always returning true.

MY if statement is clearly not working:
(*vendorName != 'q' || *vendorName != 'Q')

Anyone know why? Thanks.. Here's the code:

C++ Syntax (Toggle Plain Text) 
  1. bool getVendor(data & adata) 
  2. {
  3.     char vendorName[MAX_LEN];
  4.     char phoneNum[MAX_LEN];
  5.     char productType[MAX_LEN];
  6.     int eventNum;
  7.     char events[MAX_LEN];
  8.  
  9. 	cout << "\nPlease enter information about the winery: " << endl;
  10.     getString("\tVendor name(type q to quit): ", vendorName);
  11.  
  12.     if(*vendorName != 'q' || *vendorName != 'Q') 
  13. 	{
  14. 		getString("\tPhone number: ", phoneNum);
  15. 		getString("\tType of product: ", productType);
  16. 		eventNum = getInt("\tThe amount of events: ");
  17. 		getString("\tName(s) of events: ", events);
  18.  
  19. 		adata.setVendorName(vendorName);
  20. 		adata.setPhoneNum(phoneNum);
  21. 		adata.setProductType(productType);
  22. 		adata.setEventNum(eventNum);
  23. 		adata.setEvents(events);
  24. 		return true;
  25. 	}
  26.  
  27. 	return false;
  28. }
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Re: problems with type q to quit

 
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  #2
Mar 11th, 2009
Use && instead of || in if condition -

(*vendorName != 'q' && *vendorName != 'Q')
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Re: problems with type q to quit

 
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  #3
Mar 11th, 2009
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Originally Posted by hansel13 View Post
This subroutine is very basic, however I am struggling.

When the user types q (or Q) into the input when asked for the vendor name, the program should return false... However, this function is always returning true.

MY if statement is clearly not working:
(*vendorName != 'q' || *vendorName != 'Q')

Anyone know why? Thanks.. Here's the code:

C++ Syntax (Toggle Plain Text) 
  1. bool getVendor(data & adata) 
  2. {
  3.     char vendorName[MAX_LEN];
  4.     char phoneNum[MAX_LEN];
  5.     char productType[MAX_LEN];
  6.     int eventNum;
  7.     char events[MAX_LEN];
  8.  
  9. 	cout << "\nPlease enter information about the winery: " << endl;
  10.     getString("\tVendor name(type q to quit): ", vendorName);
  11.  
  12.     if(*vendorName != 'q' || *vendorName != 'Q') 
  13. 	{
  14. 		getString("\tPhone number: ", phoneNum);
  15. 		getString("\tType of product: ", productType);
  16. 		eventNum = getInt("\tThe amount of events: ");
  17. 		getString("\tName(s) of events: ", events);
  18.  
  19. 		adata.setVendorName(vendorName);
  20. 		adata.setPhoneNum(phoneNum);
  21. 		adata.setProductType(productType);
  22. 		adata.setEventNum(eventNum);
  23. 		adata.setEvents(events);
  24. 		return true;
  25. 	}
  26.  
  27. 	return false;
  28. }
change
cpp Syntax (Toggle Plain Text) 
  1. *vendorName != 'q' || *vendorName != 'Q'
to
cpp Syntax (Toggle Plain Text) 
  1. vendorName[0] != 'q' && vendorName[0] != 'Q'
Last edited by ivailosp; Mar 11th, 2009 at 5:42 am.
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Re: problems with type q to quit

 
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  #4
Mar 11th, 2009
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Originally Posted by ivailosp View Post
change
cpp Syntax (Toggle Plain Text) 
  1. *vendorName != 'q' || *vendorName != 'Q'
to
cpp Syntax (Toggle Plain Text) 
  1. vendorName[0] != 'q' && vendorName[0] != 'Q'
Thanks, that worked!

But that also brought about another problem.

Now if I type in any word that begins with q or Q, it returns false.

Is there away to avoid this? Because I only want the letters q and Q to return false. Not words that begin with q or Q.
Last edited by hansel13; Mar 11th, 2009 at 5:47 am.
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Re: problems with type q to quit

 
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  #5
Mar 11th, 2009
use a string comparison function rather than a pointer to the first letter in the string. Use strcmp().

Chris
Knowledge is power -- But experience is everything
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Re: problems with type q to quit

 
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  #6
Mar 11th, 2009
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Originally Posted by hansel13 View Post
Now if I type in any word that begins with q or Q, it returns false.

Is there away to avoid this? Because I only want the letters q and Q to return false. Not words that begin with q or Q.
To avoid this problem you should just compare the two strings instead of comparing the first characters ...

Try something like this:
C++ Syntax (Toggle Plain Text) 
  1. #include <iostream>
  2.  
  3. using namespace std;
  4.  
  5. int main(void)
  6. {
  7.     char input[51];
  8.     cout << "Type something: ";
  9.     cin.getline(input, 50);
  10.     cout << endl;
  11.  
  12.     if(!strcmp(input, "q") || !strcmp(input, "Q"))
  13.     {
  14.         cout << "A \"q/Q\" was detected !!!" << endl;
  15.     } else {
  16.         cout << "You typed: " << input << endl;
  17.     }
  18.  
  19.     cin.get();
  20.     return 0;
  21. }
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Re: problems with type q to quit

 
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  #7
Mar 11th, 2009
I used the strcmp() function, but now the subroutine never runs true. The if statement doesn't seem to be effective. I tried doing the following:
if(!strcmp(*vendorName, "q") || !strcmp(*vendorName, "Q"))
if(!strcmp(vendorName[0], "q") || !strcmp(vendorName[0], "Q"))
but then I got syntax errors.

Not sure what's wrong with time..

C++ Syntax (Toggle Plain Text) 
  1. bool getVendor(data & adata) 
  2. {
  3.     char vendorName[MAX_LEN];
  4.     char phoneNum[MAX_LEN];
  5.     char productType[MAX_LEN];
  6.     int eventNum;
  7.     char events[MAX_LEN];
  8.  
  9. 	cout << "\nPlease enter information about the winery: " << endl;
  10.     getString("\tVendor name(type q to quit): ", vendorName);
  11.  
  12.     if(!strcmp(vendorName, "q") || !strcmp(vendorName, "Q")) 
  13. 	{
  14. 		getString("\tPhone number: ", phoneNum);
  15. 		getString("\tType of product: ", productType);
  16. 		eventNum = getInt("\tThe amount of events: ");
  17. 		getString("\tName(s) of events: ", events);
  18.  
  19. 		adata.setVendorName(vendorName);
  20. 		adata.setPhoneNum(phoneNum);
  21. 		adata.setProductType(productType);
  22. 		adata.setEventNum(eventNum);
  23. 		adata.setEvents(events);
  24. 		return true;
  25. 	}
  26.  
  27. 	return false;
  28. }


C++ Syntax (Toggle Plain Text) 
  1. void getString(char * prompt, char * input) 
  2. {
  3.     cout << prompt;
  4.     cin.get(input, MAX_LEN, '\n');
  5.     cin.ignore(100, '\n');
  6. }
Last edited by hansel13; Mar 11th, 2009 at 7:07 pm.
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Re: problems with type q to quit

 
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  #8
Mar 12th, 2009
Anyone? I've still tried different ways to make it work, but no luck so far..
Last edited by hansel13; Mar 12th, 2009 at 3:09 am.
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Re: problems with type q to quit

 
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  #9
Mar 12th, 2009
Got it to work, thanks to everyone who helped.
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