Can anyone explain this logic?

This part of the program takes a string and print each letter on a single line, while speaking the string backwards.


To termination the For loop in the printBackwards method it's n>= 0. I originally thought it would be n==0, but using n==0 the compiler just terminates the program. I was only able to get it to work through trial and error (n>=0).

Code:

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public static void main(String[] args) {
               
                String word = "Backpack";
               
                printBackwards(word);

        }

public static void printBackwards (String s){
       
                for ( int n = length(s) - 1; n >= 0; n--){
                        System.out.println(s.charAt(n));
                       
                }
        }

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Output:

Code:

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kcapkcaB

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What will print when you compile and run this code?

Add a println to show the values of the variable n as the loop executes.

Quote:

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Originally Posted by hotsauce

I originally thought it would be n==0

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If you used that as the condition it means that the loop would only execute if n IS zero. There are 3 possibilities.

Initial value of n is zero. Condition is true. Execute loop. Change value of n. Condition is false. Exit. Loop only executes once which is pointless.

Initial value of n is zero. Condition is true. Execute loop. Never change value of n. Condition is true. Endless loop. Not very useful either.

Initial value of n is not zero. Condition is false. Never executes loop. Yet again a pointless loop.

No response from OP for a long time.

No, I'm still here. Didn't have internet for awhile.

Thanks for the explanation, it really helped.