// replace string chars with repeated char
//
#include <stdio.h>

int replace( char *p, char c)
{
  int len = 0;

  while( p[len] != 0) { p[len] = c; ++len; }

  return len;
}

int main( void)
{
  char c = 'Z', str[] = "abcdefg";

  printf( "c = %c\n", c);

  printf( "before replace: str = %s\n", str);

  int count = replace( str, c);

  printf( " after replace: str = %s\n", str);

  printf( "count = %i\n", count);
}

/* output:

c = Z
before replace: str = abcdefg
 after replace: str = ZZZZZZZ
count = 7

*/