Indentation & Comments

1. Indentation& Comments

2. Overview • Indentation isn't important to the correctness of your programs (the computer totally ignores it), but it can make a big difference to the readability of your programs.

3. Version without indentation method main(){Jeroo Sally = new Jeroo();while(!Sally.isWater(AHEAD)) {Sally.hop();}Sally.turn(RIGHT);while(!Sally.isWater(AHEAD)) {Sally.hop();}Sally.turn(RIGHT);while(!Sally.isWater(AHEAD)) {Sally.hop();}Sally.turn(RIGHT);while(!Sally.isWater(AHEAD)) {Sally.hop();}Sally.turn(RIGHT);} What does it do???

4. with indentation method main(){Jeroo Sally = new Jeroo();    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);} the meaning is easier to see

5. add in comments method main(){Jeroo Sally = new Jeroo();// Go along the top (north) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    // Go along the right (east) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    // Go along the bottom (south) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    // Go along the left (west) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    // Note that this last turn is needed to ensure that Sally is facing east    // again, as required in the problem statement.    Sally.turn(RIGHT);} now, anyone could look at the program and know exactly what it does.

6. Comments describe what is happening in the program method main(){Jeroo Sally = new Jeroo();// this is a loop     while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);// this is a loop    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);// another loop    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);  // still looping     while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    // a turn     Sally.turn(RIGHT);} NOT stating the obvious These are lousy comments!

7. refining further… • of course, there are areas of repeated code… • perfect candidates for creating methods • how would you rewrite it to be more efficient using methods? • can you still create a program as readable as the example given here?

8. add in comments method main(){Jeroo Sally = new Jeroo();    // Go along the top (north) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    // Go along the right (east) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    // Go along the bottom (south) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    Sally.turn(RIGHT);    // Go along the left (west) edge of the island    while(!Sally.isWater(AHEAD)) {        Sally.hop();    }    // Note that this last turn is needed to ensure that Sally is facing east    // again, as required in the problem statement.    Sally.turn(RIGHT);} This could be a method Repeated code makes a good method Or would this be a better choice for a method?

9. The End The important point is to make a reasonable effort to communicate to your human readers as well as to the computer. Comments and indentation are the 2 tools for making a program readable