Consider the following two examples:
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| Click on the image to enlarge |
I have 2 questions for you now.
1) Will both the loops take the same time to execute?
2) Which is a better programming approach?
75% of the programmers would say, there will not be any changes, both the loops will execute identical. Who knows you may also think that way, I bet you are gonna change that opinion by end of this article. Or at least know why we follow something as a ‘best practice’
Let us analyze both the situations. In both cases there are 3 executable statements viz two for loops and one Print statement.
Assumption : Let us assume that every executable statement takes 1 second to execute
Let us analyze the first situation:
Let us go line by line,
Line 1 (For i=1 to 100) : This will be executed for 100 positive conditions and 1 negative condition. Total 101 executions, there by taking 101 seconds
Execution time for line 1 = 101 seconds
Line 2 (For j=1 to 5) : This statement will be executed for 5 positive conditions and 1 negative condition. Total 6 executions for every positive conditions of line 1, which will be 100. So making it 100x6 executions which will be 600.
Execution time for line 2 = 600
Line 3 (Print “Hello”) : For statement will be executed for every positive condition of Line 1 and Line 2. Therefore, 100x5 times it will be executed.
Execution time for line 3 = 500
Therefore the total execution time for first situation = 101 + 600 + 500 = 1201 seconds
Let us now analyse the second situation:
Let us again go line by line,
Line 1 (For j=1 to 5) : This will be executed for 5 positive conditions and 1 negative condition. Total 6 executions, there by taking 6 seconds
Execution time for line 1 = 6 seconds
Line 2 (For i=1 to 100) : This statement will be executed for 100 positive conditions and 1 negative condition. Total 101 executions for every positive conditions of line 1, which will be 5. So making it 5x101 executions which will be 505.
Execution time for line 2 = 505
Line 3 (Print “Hello”) : For statement will be executed for every positive condition of Line 1 and Line 2. Therefore, 5x100 times it will be executed.
Execution time for line 3 = 500
Here the total execution time for 2nd situation = 6 + 505 + 500 = 1011 seconds.
Did you ever realize this??? Yes, Always remember...
We should have the lesser iteration loop in the outer and more iterations loop inner.
Original Post: http://www.qtphelp.com/search/label/QTP%20Tips
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