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I am working on an assignment and I have been noticing a problem in my coding assignment. It is not clear to me how to tackle this problem, probably due to a lack of sleep but anyway. I need to trim a char array of it's white spaces for this assignment.

The solution I thought of involved a second char array and just simply copy the non white spaces to that array and I'm done. But how can I create a char array without knowing it's size, because at that moment I do not yet know the size. I still need to trim it in order to know how many characters need to be copied to the new array, which varies in the assignment

I know there are a lot of good questions out here on stackoverflow but I think this has more to do with the thought process rather then the correct syntax.

My second problem is how do I perform a fscanf/fgetc on a char array since it needs a stream, is it sufficient to give it a pointer rather then a stream?

Gene Arboit
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Kipt Scriddy
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  • C-style strings are terminated by the `\0` character, so even if you make the new array as large as the original, you can just zero-out the remaining bytes – skirkpatrick Feb 23 '13 at 03:31
  • Okay so if I understand it. Just make a new char array and when I finish reading the original char array I just close it with a \0? – Kipt Scriddy Feb 23 '13 at 03:33
  • For your first question, use http://stackoverflow.com/questions/122616/how-do-i-trim-leading-trailing-whitespace-in-a-standard-way – Gene Arboit Feb 23 '13 at 03:33
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    @GeneArboit Edits that you make should be substantial and should fix multiple issues with the post. Minor edits are not encouraged. – asheeshr Feb 23 '13 at 03:37
  • Do you need to use `fscanf`/ `fgetc` ? – asheeshr Feb 23 '13 at 03:37
  • I am not sure, I did read about a couple of other posts on stackoverflow and a couple of them suggested it [link to post](http://stackoverflow.com/questions/1458131/remove-extra-white-space-from-inside-a-c-string). – Kipt Scriddy Feb 23 '13 at 03:47

2 Answers2

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If making the change in-place simply, shift every chracter after a space back, and repeat till the end of the array. This is very inefficient.

If making a new copy, make a new array of the same length, and then do as you were doing (copy all the non-space characters). If you copy the \0 character as well, then there will be no string termination issue. This is much more efficient.

Going by your comments, it appears you may have the option to input the array in any form you wish. I would then recommend that instead of doing text manipulations later on, just input the string in the form you need.

You can simply use scanf or fscanf repeatedly, to input the separate words into the same array. This will take care of all the whitespaces.

asheeshr
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Here is one partial idea: You can make a first pass on the char array and count the blanks, then take the string length minus the blanks for the second array, then perform your copy across skipping the blanks.

You could also create a pass through the array:

Test until end of array:

Is my (Current/Index) position blank? (A space)

If so, grab next available non-blank value and put it there.

then index++

If not, index++

Not sure on the second, will do some checking and see if I can find a good answer there too.

Raymond Schenk
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