Remove char from char* and return char* - c

Question

I have one char array and I want to delete chars that satisfy my condition. Example I have a char array A={1,-1,0 ,1 ,-1} and I want to delete elements that equal -1. That mean output is {1,0,1}, and I want to check how many element in the array. In my example is 3. Can you help me please?
char* delete_char(char* sourceArray, char inputChar)
{
char* out=NULL;
//Need to malloc memory. But I don't know how many size will allocate because it depends on how many element that don't equal -1
return out;
}
int sizeofArray(char* sourceArray)
{
return size;
}

Answer 1

You have some strategies:
Calculate the exact size before allocating.
Estimate a size.
Allocate a big size memory (you probably know maximum size in worse case).
In two later cases, you can use realloc to shrink the memory. In your code, the estimated size is strlen(sourceArray)+1 if the array is a zero-terminated string, because by deleting the result is less and equal to it.

Answer 2

First of all, when you are using char* as an array, you also need to provide information about the length of that array (how many items it contains). Usualy this is done by a second parameter.
In your case: delete_char(char *inputArray, char inputArraySize, char inputChar).
Then you should allocate your result array to be the size of your input array (because it can contain at most as much items as the input array).
After that, you should iterate through every item in the input array and if the item fulfills your condition, add it into the result array. Of course, you have to provide also the size of the output array (for instance in an another output parameter), so you'll be able to work with it.
And lastly, when your done with working with the resulting array, don't forget do deallocate all of its memory (that means deallocate it as it was the size of the original input array, because it actially is).

Answer 3

You can write own function like that.
int size(char *ptr)
{
int offset = 0;
int count = 0;
while (*(ptr + offset) != '\0')
{
++count;
++offset;
}
return count;
}

Answer 4

Here it is:
#include <string.h>
char* delete_char(char* sourceArray, char inputChar)
{
int iNr = 0,iSize,j = 0;
iSize = strlen( sourceArray );
for( int i = 0; i < iSize; i++ )
if( sourceArray[i] == inputChar )
iNr ++;
char *newarray = new char[iNr +1];
for( int i = 0; i < iSize; i++ )
{
if( sourceArray[i] != inputChar )
newarray[j++] = sourceArray[i];
}
return newarray;
}
int sizeofArray(char* sourceArray)
{
return strlen( sourceArray );
}
PS TESTED. It works but may not be very efficient cause you check it 2 times.

Answer 5

You can scan the array to determine the number of elements you are removing, then allocate and appropriate memory, then copy. For example:
int sizeNeeded = 0;
for (int i = 0; i < sizeofArray(sourceArray; i++) {
if (sourceArray[I] != inputChar) sizeNeeded++;
}
char *rv = (char *) malloc(sizeNeeded * sizeOf(char));
int j = 0;
for (int i = 0; i < sizeofArray(sourceArray; i++) {
if (sourceArray[I] != inputChar) rv[j++] = sourceArray[i];
}
I did not try to compile this code but it should convey the idea