could someone explain the changes of the variable N for me, and explain why. you help would be appreciated....
Code:#include <stdio.h> void hanoi(int n,char from,char aux,char to) { if (n==0){ return;} hanoi(n-1,from,to,aux); printf("\nMove disk %d from %c to %c",n,from,to); hanoi(n-1,aux,from,to); } void main(void) { hanoi(3,'a','b','c'); getchar(); }
void main(void) should be int main(void) and 0 should be returned upon a successful return from main().
Now with that said, what is the actual question? The phrase "changes of the variable N" sort of seems to say that you want to know how n changes. n changes because the function itself is passing a modified value of n, namely n-1, to itself.
It's not really that complicated if you can understand that a function can simple call itself, and then it returns to itself. Also, you need to remember that one call to a function is separate to another call of a function (except as related to the parameters being passed).
If you could clarify your question, you might receive a better answer, since I don't think this answer is that good.
when the print statment is executed for the entire program the the 7 output result for the variable n is 1 , 2, 1, 3, 1, 2, 1........what i would like to know is how those values are arrived at...
Uh.... Trace the program.
First time you put 3, before it prints, it calls the function again. That's passed 2. Before it prints, it calls the function again. That's passed 1. Before it prints, it calls the function again. That's passed 0. It sees 0 has been passed, and returns.... etc. etc..
Trace it out manually on paper.
Perhaps throw in another output statement:
Code:void hanoi(int n,char from,char aux,char to) { printf("hanoi(%d,'%c','%c','%c')\n", n, from, aux, to); if (n==0){ return;} hanoi(n-1,from,to,aux); printf("Move disk %d from %c to %c\n",n,from,to); hanoi(n-1,aux,from,to); }
7. It is easier to write an incorrect program than understand a correct one.
40. There are two ways to write error-free programs; only the third one works.*
i am starting to understand but how do i know what number to return to after it pass 0. since it doesnt return 1 all the time
What do you mean? The function returns void, which means it doesn't return anything....
i am starting to get a bit confuse myself...........i understand that the print statement is going to be executed 7 times........explain how the values of N is derived at each time it prints...
I already explained that. n-1 is how it's done, because it's always being called.
Something like this:
Code:Call 1, n = 3 Call 2, n = 2 Call 3, n = 1 Call 4, n = 0, return print Call 5, n = 0, return print Call 6, n = 1 Call 7, n = 0, return print Call 8, n = 0, return print Call 9, n = 2 Call 10, n = 1 Call 11, n = 0, return print Call 12, n = 0, return print Call 13, n = 1 Call 14, n = 0, return print Call 15, n = 0, return
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
