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How would I go about using a value of user input to limit the terms in a for loop. The objective of the program is to let the user input the amount of terms, starting value, and counting interval. Thanks!

Ryan Allen
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2 Answers2

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Your question is simple to answer by consulting TIBasicDev, specificly the pages for Input, Prompt, and For(. Input and Prompt are self explanatory; they serve as two means of retrieving input from the user. For( can take arguments to exhibit the behaviors you want.

Prompt

Prompt is smaller and dirtier. The program 

Prompt A

will result in the following output.

A=?

Input

Input is the larger and cleaner option. The program

Input "ENTER VALUE:",A

will result in the following output

ENTER VALUE:

For

Taken from TIBasicDev:

The For loop takes four arguments: the variable (A-Z or theta), the starting value, the ending value, and the increment. It counts from the starting value to the ending value at the specified increment.

...

Format
:For(variable,start,end[,increment])
:Command(s)
:End

Writing your program will now simply require using the input commands to retrieve user input then using the for loop to create the desired effect.

ankh-morpork
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As dohaqatar7 said, you can achieve your goal using the basic input commands. However, there is also a (slightly more advanced) way to allow users to input the values all at once, separated by commas. To do this, you input a string, store it into a built-in string variable like Str1, then convert it to a list of numbers, and finally access each element of the list for the parameters in your For( loop.

Input "START,END,STEP: ",Str1        //Whatever is input goes into Str1 as a string
                                     //For example, "1,100,2"
expr("{"+Str1                        //Then it is converted into a list like {1,100,2}
For(X,Ans(1),Ans(2),Ans(3)           //Evaluates to For(X,1,100,2
[your code]
End

expr( means expression, and basically tells the calculator to evaluate the string passed to it. But first, a { is tacked on to the front so the calculator interprets it as a list, which is stored into the Ans variable. Individual elements of a list are accessed in the format [listname] (position), so Ans(1) will get the first element of the list (in this case the start value 1) and so on.

lirtosiast
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