Repeating a text string
In this lesson we will see how to write a custom function that builds a string by repeating a given string a certain number of times.
Our custom function
We are going to write the function
repeatedString(pBaseString, pRepeatCount), the function concatenates the pBaseString parameter as many times as specified by pRepeatCount to build a long repeated string. It does this by using a repeat loop to build the string, appending the string to the return value as many times as needed.
The function will be called with a statement such as one of the following.
get repeatedString(space,20) -- returns 20 spaces
put repeatedString("abc",2) into myString -- returns "abcabc"
set the setupString of me to repeatedString(it,1000)
get repeatedString("A") -- returns "A"
Our example stack
We will create an example stack which will allow us to specify the parameters, call the function and display the result.
The repeatedString function
function repeatedString pBaseString, pRepeatCount ## Check that pRepeatCount is a valid number ## If the function is called with an empty repeat count we use 1 as a default value if pRepeatCount is empty or pRepeatCount is not an integer then put 1 into pRepeatCount end if repeat for pRepeatCount put pBaseString after tFinalString end repeat return tFinalString end repeatedString
The after keyword
We use the after keyword to build the final string. We have chosen to use the put...after form of the put command to build the string because, in general, the put...after form is faster than the put...before form or using the & or && operators.
If you are dealing with fairly short strings and a fairly low number of repetitions--under a hundred--the time savings may not be significant, but when building a repeated string with thousands or tens of thousands of repetitions, using the put...after form may save as much as several seconds. The time difference becomes even more pronounced the longer the string becomes.
Calling the function from the button
Now all we need to do is call the function from the Generate String button and put the result into the result field.
on mouseUp put field "base string" into tBaseString put field "repeat count" into tRepeatCount put repeatedString(tBaseString, tRepeatCount) into field "result" end mouseUp
It's easy to modify this handler to create new variations. For example, suppose you want the base string to be repeated on every line, instead of just concatenated. You can do this by changing the line inside the repeat loop as follows:
put pBaseString & return after tFinalString