Quick question (beginner)

[JMaxwell]

The following code fragment:

#include <iostream>
#include <string>

using namespace std;

int main() 
{
char input[300], *p, *q[300], **r = q;

 cin.getline(input, 300);

 for (p = input; *p; p++)
   switch (tolower(*p)) {
   case 'e':
     *r++ = p;
     break;
   case '.':
   case '\'':
   case ' ':
     *p = '\0';
     break; }
 *r = 0;

 for (r = q; *r; r++)
   cout << *r << " ";

 cout << endl;
}

was given as an example exam for my introduction programming course. What i don't understand is the use of the *p and *r as the middle argument in the for loops. I've only used inequalities for that location, so i have no idea what that means for pointers. Any help is appreciated.

[laserlight]

You need to indent the code properly to see more clearly what it is doing. Also, just post the code as-is within the code tags; don't try to apply any formatting as the forum software will apply it for you.

[JMaxwell]

You need to indent the code properly to see more clearly what it is doing. Also, just post the code as-is within the code tags; don't try to apply any formatting as the forum software will apply it for you.

ok, done.

[ZuK]

What i don't understand is the use of the *p and *r as the middle argument in the for loops.

*p and *r dereference the pointers thus getting the value of a character.
C interprets any integral value 0 as false. Therfore the loop ends when the '\0' character is found and that is the end of string marker.
Kurt

[JMaxwell]

*p and *r dereference the pointers thus getting the value of a character.
C interprets any integral value 0 as false. Therfore the loop ends when the '\0' character is found and that is the end of string marker.
Kurt

Thanks, i didn't realize that the null character was taken as false when used as a boolean expression.
One last question though:
I've seen *r=*p and r=p and understand the difference but what does the expression **r=q mean in this case?

[ZuK]

what does the expression **r=q mean in this case?

This is an initialisation and initializes the pointer to pointer of char r with the value q and that is an array of 300 pointers to char and is compatible with a pointer to pointer to char.
Kurt