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For the 2018-2019 school year, we have switched to using the WLMOJ judge for lesson information, no new lessons will be added here.

The following provides an overview of counted loops:


Turing

for i : startValue .. endValue
	% code
	% code
end for

Python

for iteratingVariable in sequence:
	# code
	# code

Java

for (initial condition; condition; increment) {
	// code
	// code
}

The following example will make the use of these loops clearer. Let’s say we wanted to print Hello World! 5 times. We could accomplish this as follows:


Turing

for i : 1 .. 5
	put("Hello World!")
end for

Python

for i in range(1, 5):
	print("Hello World!")

Java

for (int i = 0; i < 5; i++) {
	System.out.println("Hello World!");
}

But, what if we wanted to increment by a number other than one? For example, to output all the multiples of 3 from 1 to 14, we could iterate from 1 to 14 and use conditionals to check for multiplicity. However, we can achieve the same result using loops as follows. (We know that the first number will be 3)


Turing

for i : 3 .. 14 by 3
	put i
end for

Python

for i in range(3, 15, 3): # 15 because we want to go to 14 and Python's ranges are closed at the end.
	print(i)

Java

for (int i = 3; i <= 14; i += 3){
	System.out.println(i);
}

Practice

Use counted loops to output a 5 by 5 times table as follows:

1 2 3 4 5
2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
5 10 15 20 25