Turing/Control Structures and Logical Expressions
For all of these codes, don't forget to put end if/loop/for at the end of the if/loop/for statement.
Now, try this code:
var text : string get text if (text = "Hello") then put "Hello, world" elsif (text = "Bananas") then put "Bananas are good" else put "Bye." end if
- If the user enters "Hello, world" then the output is "Hello"
- If the input is "Bananas" then the output is "Bananas are good"
- If the input is anything else, then the ouput is "Bye."
Loops do exactly what they sound like. The program from the loop to the end loop Try this code:
var a : int := 0 loop put a a := a + 1 end loop
This program should output numbers indefinitely from 0 up. Now, let's say that we want to only put the numbers from 0 to 100. We need to put an 'exit when' statement.
var a : int := 0 loop put a exit when a = 100 %put the exit when right here a := a + 1 end loop
For statements are really useful. The program:
for i : small..big by intervals end for
is the same as
var i : real := small loop exit when i = big i := i + intervals end loop
If that was confusing, a for statement pretty much gives the variable 'i' all the values from small to big.
for i : 1..10 put i, ", " end for
1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
They are really useful for assigning values to an entire array, for example, this program gives the value '0' for every value in the array.
var asdf : array 1..10,1..10 of int for i : 1..10 for j : 1..10 asdf (i,j) := 0 end for end for
- Make the user input a user name and password. (Hint: If statement)
- Make the program give the user as many tries as they want, or if you want a challenge, 5 tries (Hint: Loop)
- Re-do exercise 2 (input 10 values from an array) from the last one, with for statements
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