Replacing several characters in string with one in C - c

Question

I need to replace several characters with one (depending if their count is even or odd). If it's even i should replace + with P, if it's odd with p.
Input: kjlz++zux+++
while(p[i])
{
j=i;
k=i;
length=strlen(p);
if(p[i]=='*')
{
position=i;
}
printf("Position is: %d", position);
while(p[j]=='*')
{
counter++;
j++;
}
}
Output: kjlzPzuxp
Im not sure how to remove several characters I know how to input one.

Answer 1

Basically you can leave the text variable intact until you find a +. In that case you start counting how many consecutive plusses there are. Once you know this, it can be decided if you should add a letter P or p. Keep a separate index to write back to your text variable! Otherwise it would start writing to the wrong index after 2 or 3 plusses are found, try to figure out why ;).
#include <stdio.h>
#include <stdlib.h>
int main (void)
{
char text[] = "kjlz++zux+++";
int len = sizeof(text) / sizeof(text[0]);
int index = 0, count = 0;
for(int i = 0; i < len; i++)
{
if(text[i] == '+')
{
count = 0;
while(text[i] == '+') i++, count++;
i--;
text[index++] = count % 2 ? 'p' : 'P';
}
else
{
text[index++] = text[i];
}
}
text[index] = 0;
printf(text);
}
You could allocate space for the text variable with malloc so that you can use realloc afterwards to shrink the array to the size of the output text. This way some memory is saved, this is especially important when you start working with bigger chunks of data.

Answer 2

If I have understood correctly you do not know how to implement a corresponding function.
It can look the following way as it is shown in the demonstrative program.
#include <stdio.h>
char * replace_pluses( char *s )
{
const char plus = '+';
const char odd_plus = 'p';
const char even_plus = 'P';
char *dsn = s;
for ( char *src = s; *src; )
{
if ( *src == plus )
{
int odd = 1;
while ( *++src == plus ) odd ^= 1;
*dsn++ = odd ? odd_plus : even_plus;
}
else
{
if ( dsn != src ) *dsn = *src;
++dsn;
++src;
}
}
*dsn = '\0';
return s;
}
int main(void)
{
char s[] = "kjlz++zux+++";
puts( s );
puts( replace_pluses( s ) );
return 0;
}
The program output is
kjlz++zux+++
kjlzPzuxp
Or you can write a more generic function like this
#include <stdio.h>
char * replace_odd_even_duplicates( char *s, char c1, char c2, char c3 )
{
char *dsn = s;
for ( char *src = s; *src; )
{
if ( *src == c1 )
{
int odd = 1;
while ( *++src == c1 ) odd ^= 1;
*dsn++ = odd ? c2 : c3;
}
else
{
if ( dsn != src ) *dsn = *src;
++dsn;
++src;
}
}
*dsn = '\0';
return s;
}
int main(void)
{
char s[] = "kjlz++zux+++";
puts( s );
puts( replace_odd_even_duplicates( s, '+', 'p', 'P' ) );
return 0;
}