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Emptying char MAX_PATH array?

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Emptying char MAX_PATH array?

 
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  #1
May 31st, 2009
This is a very simple problem, but for some reason I can't get it to work. I need to empty a variable ( char fileName[MAX_PATH] =""; ).

It needs to be to where when I use this that it sees if it equals "", this wont work if it equals NULL will it?:
CPP Syntax (Toggle Plain Text) 
  1. if (fileName = "")
  2. {
  3. }

How could I do this? I have tried:
CPP Syntax (Toggle Plain Text) 
  1. fileName = "";
  2. fileName = NULL;
  3. fileName[MAX_PATH] = "";

Those all return errors, why can't I empty the variable?
Last edited by killdude69; May 31st, 2009 at 2:33 am.
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Re: Emptying char MAX_PATH array?

 
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  #2
May 31st, 2009
Use memset...

memset(fileName, 0, MAX_PATH);

Rewrites the elements to 0.
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Re: Emptying char MAX_PATH array?

 
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  #3
May 31st, 2009
Keep it simple:
C++ Syntax (Toggle Plain Text) 
  1. fileName[0] = '\0';
  2. // or even
  3. *fileName = 0;
  4. // to test:
  5. if (*fileName) { // non-empty
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Re: Emptying char MAX_PATH array?

 
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  #4
May 31st, 2009
How would I test if it IS empty.
Because I am currently using: if (fileName == "")

And I am using this for over 6 if statments.
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Re: Emptying char MAX_PATH array?

 
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  #5
May 31st, 2009
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Originally Posted by killdude69 View Post
How would I test if it IS empty.
Because I am currently using: if (fileName == "")

And I am using this for over 6 if statments.
Didn't you familiar with logical not operator?
C++ Syntax (Toggle Plain Text) 
  1. if (!*fileName)
  2. // or
  3. if (fileName[0] == '\0')
  4. // or
  5. if (strlen(fileName) == 0)
By the way, fileName == "" is equal to false in all cases. Why? Think about pointers comparison
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Re: Emptying char MAX_PATH array?

 
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  #6
May 31st, 2009
I know how to use logical operators, I just wasn't sure if !* was even valid.

the strlen() aproach seems best to me ArkM, I will try it.
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Re: Emptying char MAX_PATH array?

 
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  #7
May 31st, 2009
Sorry for the DP, but I just want to let you know, ArkM, that that worked perfectly. Thanks to you to Yiucia, I used your memset approach. Rep for you all. Problem solved.

And just so you know, I am a decent programmer, don't be fooled by this simple question
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