/* Covers some of the basics of strings, especially about the string 
   terminating character '\0' = 0.
*/

#include <iostream.h>

#include <ctype.h>
/* contains character functions, such isuppper, tolower */

#include <cstring>

void chop(char*);  /* When passed to a function, the pointer type char* is
                      the same as the array type char[].
		   */

void main(){

  char cc, text[70], pet[4], *d, w[4];
  int occupied, reserved;

  strcpy(text,"A string constant.");

  /* cannot say text = "A string constant." (except as initialization)*/

  occupied = strlen(text);

  reserved = sizeof(text)/sizeof(char);

  cout << "occupied = " << occupied << ", reserved = " 
       << reserved << ".\n";

  if (isupper(text[0])) cc=tolower(text[0]);

  cout << text << endl << cc << endl;

  /* If the first character is uppercase, the next statement changes it
     to its lowercase version.
  */
  if (isupper(text[0])) text[0]=tolower(text[0]);

  cout << text << endl;

  chop(text);
  cout << text << endl;

  text[1]='?';
  cout << text << endl;

  chop(text);
  cout << text << endl;

  pet[0]='c'; pet[1]='a'; pet[2]='t'; pet[3]=0;   /* '/0'==0 */

  cout << pet << endl;

  d = pet;             /* this is OK since d is a pointer, not an array */
  cout << d << endl;

  strcpy(w,pet);       /* w=pet is not allowed. must use the function
                          strcpy from cstring.h
		       */
  cout << w << endl;
}

/* takes a string and replaces the first bit of white space (either
   ' ' or '\n') with the string terminating character '\0'
*/
void chop (char* a){

  int i=0;
  while (1){         // infinite loop
    if (a[i]==' ' || a[i]=='\n')
      a[i]='\0';
    if (a[i]=='\0')
      return;
    i++;
  }
}