clearing a char array c

Question

I thought by setting the first element to a null would clear the entire contents of a char array   char my custom data 40     Hello    my custom data 0      0     However  this only sets the first element to null   or  my custom data 0    0     rather than use memset  I thought the 2 examples above should clear all the data

User · Answer

I thought by setting the first element to a null would clear the entire contents of a char array.

That is not correct as you discovered

However, this only sets the first element to null.

Exactly!

You need to use memset to clear all the data, it is not sufficient to set one of the entries to null.

However, if setting an element of the array to null means something special (for example when using a null terminating string in) it might be sufficient to set the first element to null. That way any user of the array will understand that it is empty even though the array still includes the old chars in memory

User · Answer

An array in C is just a memory location  so indeed  your my custom data 0      0   assignment simply sets the first element to zero and leaves the other elements intact   If you want to clear all the elements of the array  you ll have to visit each element  That is what memset is for   memset  amp arr 0   0  sizeof arr      This is generally the fastest way to take care of this  If you can use C    consider std  fill instead   char  begin    amp arr  char  end   begin   sizeof arr   std  fill begin  end  0

User · Answer

How about the following   bzero my custom data 40

User · Answer

Pls find below where I have explained with data in the array after case 1  amp  case 2   char sc ArrData  100    strcpy sc ArrData  Hai       Case 1    sc ArrData 0      0     Result   -    sc ArrData   0  0     1  97  a   2  105  i   3  0      Case 2    memset  amp sc ArrData 0   0  sizeof sc ArrData      Result   -    sc ArrData   0  0     1  0     2  0     3  0      Though setting first argument to NULL will do the trick  using memset is advisable

User · Answer

You should use memset   Setting just the first element won t work  you need to set all elements - if not  how could you set only the first element to 0

User · Answer

Why not use memset    That s how to do it   Setting the first element leaves the rest of the memory untouched  but str functions will treat the data as empty

User · Answer

Try the following   strcpy my custom data

User · Answer

I usually just do like this    memset bufferar    0   sizeof bufferar

User · Answer

Use   memset my custom data  0  sizeof my custom data      Or   memset my custom data  0  strlen my custom data

User · Answer

void clearArray  char  input          input

User · Answer

Nope  All you are doing is setting the first value to   0  or 0   If you are working with null terminated strings  then in the first example  you ll get behavior that mimics what you expect  however the memory is still set   If you want to clear the memory without using memset  use a for loop

User · Answer

Writing a null character to the first character does just that   If you treat it as a string  code obeying the null termination character will treat it as a null string  but that is not the same as clearing the data   If you want to actually clear the data you ll need to use memset

User · Answer

It depends on how you want to view the array   If you are viewing the array as a series of chars  then the only way to clear out the data is to touch every entry  memset is probably the most effective way to achieve this   On the other hand  if you are choosing to view this as a C C   null terminated string  setting the first byte to 0 will effectively clear the string

User · Answer

Why would you think setting a single element would clear the entire array  In C  especially  little ever happens without the programmer explicitly programming it   If you set the first element to zero  or any value   then you have done exactly that  and nothing more   When initializing you can set an array to zero   char mcd 40     0      sets the whole array      Otherwise  I don t know any technique other than memset  or something similar

User · Answer

Try the following code   void clean char  var        int i   0      while var i       0             var i      0           i

User · Answer

set the first element to NULL  printing the char array will give you nothing back

[c] clearing a char array c

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