Now that we are familiar with the Debug Perspective, we can trace + the execution of our program and monitor the variables. We will do a click + by click run through of a few lines of our program. To trace through + execution of the loop, click on the 'Step Into' button.
In our initial state, you will see that the blue arrow points + to the first line of our script. This line initializes the $output + variable. Since the line hasn't been executed yet, you will see both + $i and $output are unitialized.
After one click of the Step Into button, the blue arrow moves + to the first line of our for loop. Again, this line has not been + executed, so $i is still uninitialized, but $output has now been + initialized to ''.
After two more clicks, we are into our for loop. The Variables + window tells us that $i is 0 and $output is still ''.
After another click, $output has been assigned the value + 'Loop0'.
After another click, $i is incremented and now has the value + 1. The console displays the output 'Loop0', which is the result of + the echo statement. The blue arrow has returned to the top line of + the for loop, ready for another iteration.
By continuing in this manner, we can see the values of + each variable as execution of our script progresses and we can monitor the + output after each line of the script..