DelphiScript - Working With Strings

Basics

Special characters

Getting the string length

Concatenating strings

Comparing strings

Accessing individual character of a string

Searching for characters and substrings

Getting a substring

Splitting strings

Removing extra spaces from a string

Replacing characters and substrings

Changing the letter case

Working with string lists

A string is a sequence of symbols or digits. Strings are among the most frequently used data types. Like any other data type, strings in TestComplete are represented as OLE-compatible variants.

In DelphiScript, a sequence of literal characters enclosed in single quotation marks (') is recognized as a string. Double quotation marks (") are allowed within a string. To insert a single quotation mark into a string, it should be duplicated. The following is an example of string:

To deal with strings, TestComplete has a special aqString scripting object. The object is available for all supported scripting languages, so that you can use it to operate with string values regardless of the chosen language.

Another scripting object that is useful for string manipulation is aqConvert. This object has several methods that convert values of different types to a string representation and vice versa.

Furthermore, you can use native DelphiScript functions that operate with strings. The table below lists these functions:

In DelphiScript you can emulate any character by using the Chr function with the appropriate ASCII code. Another way to emulate a character is to prefix its ASCII code with # symbol. This also applies to special characters that are used to format string values. The table below lists the most frequently used special characters.

Characters returned by Chr function should be joined to the string by concatenation:

The # symbol notation can be used both in concatenation with a string and within the string text (when enclosed in single quotation marks):

To obtain the total number of characters in a string you can either call the aqString.GetLength method, or call DelphiScript's Length function. The character position in DelphiScript is not zero-based, so the maximum position number in a string is equal to the string length. The following code demonstrates both ways of obtaining the string length:

Using TestComplete, you can limit the length of string parameters returned by functions of the tested application. For this purpose, use the Maximum string length of [out] parameters project property. If the length of the string returned from the application via one of its out parameters exceeds the property’s value, TestComplete treats the returned string as a null one.

The operation that forms a string out of several others is called concatenation. The aqString object has the aqString.Concat method that performs this operation.

However, it is much more convenient to use the addition operator (+) for this purpose. If one of the addition operands is a string, then the performed operation is considered to be string concatenation rather than number addition.

This sample code shows how to make a string out of several substrings:

The comparison of two strings is widely used during testing. Generally a test procedure obtains textual data (user input, file contents, property value and so on) and then compares it with the expected data. The TestComplete aqString object has a specific method aqString.Compare that compares one string value to another. The aqString.Compare method has three parameters: two of them - String 1 and String2 specify the strings to be compared, while the last parameter defines whether the comparison should be case-sensitive or not.

You can also use the equality operator of DelphiScript to perform case-sensitive comparison.

Both of the methods can compare strings holding specific national symbols, for example characters with diacritical marks ( , , and others).

The code below demonstrates the specifics of the above-mentioned methods.

The string data type can hold as series of characters as well as individual characters. In DelphiScript strings are implemented as one-dimensional arrays. This allows you to extract a single character out of the string. Besides, you can perform the same action using the aqString.GetChar method. Note however, that the index within DelphiScript arrays is one-based, whereas the index for the GetChar method is zero-based.

The sample routine below illustrates both approaches, it posts the given text to the TestComplete log in two different ways: as a whole string and by a single letter.

One of the most common tasks that one has to perform when working with string values is determining whether specific text is part of a string. To perform such tasks, the aqString object has the Find method. If the specified substring was found, the method returns the number of the first occurrence of the substring within the source string. If the specified substring was not found, the method returns -1:

You can also get the position where the specified substring occurs using the native DelphiScript function Pos. If the substring was found, the function returns the initial position (from 1) of the first substring match. If no occurrences were found, then it returns 0. The code below demonstrates how to use it:

DelphiScript has a special routine named Copy that allows you to extract a substring out of a string. The function returns a text fragment that starts at a given position and has a specified length. Negative and zero values for positions are interpreted as the first character in a string. If the specified length is greater than the string length, then the substring lasts until the end of the initial string. If length parameter is negative or zero then the empty string is returned.

The aqString object also has a similar method - SubString that returns a substring starting from the specified position and having the given length. However, this method cannot accept negative values, and the position numbers are zero-based.

The sample code below demonstrates how to use both of the routines:

Sometimes it is required to make several strings out of a single string. This operation splits a string into substrings. In DelphiScript this operation can be performed by the aqString.GetListItem. It extracts a substring with the specified index out of the input string. It was designed to read the items from a string lists (see Working with string lists for more information). However it allows to redefine the delimiter characters and be used to get sentences, separate words and so forth.

The aqString object has a special routine aqString.Trim that excludes the leading, trailing spaces, or both, from a string. Generally this method is applied to remove the "useless" spaces in the beginning or end of the strings obtained from the user input.

Another function that can be useful when handling user input strings is excluding extra inner spaces out of the string. This function seems to be similar to Trim, but the latter only removes spaces at the beginning or end of the string and does not affect the spaces within the string. The general idea of the function is for the string to be parsed into separate words and then a new string is constructed. The new string consists of the same words but is separated with a single space between words.

Quite often we need to find and replace a character or substring within a string. There are two ways to do this: by using the aqString.Replace method or using the RegExpr.Replace method provided by the HISUtils plugin.

The aqString object method is much easier to use and can be applied when you need to change a definite character or string. It allows you to set whether the search should be case-sensitive or not. Here is an example of how to use this method:

The RegExp object method is a little more complicated, but it offers more flexibility. You can change not only a definite character or string, but all fragments matching the specified regular expression pattern. However, you have to create an instance of RegExp object and set the pattern before replacing. The regular expression pattern is defined via the RegExpr.Expression property. Besides, there are certain flags that are set by the RegExpr.ModifierStr property, which affect the search procedure. The most frequently used modifiers are: i - search ignoring the letter case, m - perform multiline search and s - treats a string as a single line. Read the Regular Expressions Syntax topic to learn how to compose regular expressions. The first sample demonstrates how to change a definite string using the Replace method.

The second example shows how to replace a substring with alternative parts. The patterns of alternative parts are separated by pipe characters (" | "). For instance, in the sample below the /ht(ml|m)/ pattern matches both html and htm:

Furthermore, using regular expressions you can search for the text fragments that match the specified format. In the next sample, all dates written in the DD/MM/YYYY format are substituted with the Some Date string. This operation can be useful, for example, when comparing two reports that contain the generation date.

Capital and lower case letters can be included in a string. The TestComplete aqString object has special methods that convert uppercased letters to lower case and vice versa. They are: aqString.ToLower and aqString.ToUpper.

The code below demonstrates how these methods are applied.

Some scripting objects, generally, controls like ListBoxes, ComboBoxes, Memos, return data about their state or contents as string lists. The individual data elements (or items) in this list are separated by commas, line breaks, carriage returns or some other delimiter characters.

The aqString object has a number of specific methods (AddListItem, ChangeListItem, DeleteListItem, GetListItem and GetListLength) that are intended to deal with such lists of textual data. The AddListItem and DeleteListItem, respectively, append the item to the list, or remove the item from the list. The GetListItem method retrieves the item with the given index, and ChangeListItem assigns a new value to the given item. The GetListLength method returns the total number of items in the string list.

The symbol that is used as the separator of list items is defined by the ListSeparator property. By default the list separator is a pipe character "|", but it can be reassigned to comma, column, line break, carriage return, tabulation, and any other printable and non-printable character, or even to several characters.

Here is the sample code that shows how to operate with the string lists returned by scripting objects.