Ordinal types include integer, character, Boolean, enumerated, and subrange types. An ordinal type defines an ordered set of values in which each value except the first has a unique predecessor and each value except the last has a unique successor. Further, each value has an ordinality, which determines the ordering of the type. For integer types, the ordinality of a value is the value itself. Subrange types maintain the ordinalities of their base types.
For other ordinal types, by default the first value has ordinality 0, the next value has ordinality 1, and so forth. The declaration of an enumerated type can explicitly override this default. Several predefined functions operate on ordinal values and type identifiers. The most important of them are summarized below. For example, High Byte returns because the highest value of type Byte isand Succ 2 returns 3 because 3 is the successor of 2.
The standard procedures Inc and Dec increment and decrement the value of an ordinal variable. The platform-dependent integer types are transformed to fit the bit size of the current compiler platform. Using these types whenever possible, since they result in the best performance for the underlying CPU and operating system, is desirable. The following table illustrates their ranges and storage formats for the Delphi compiler.
Platform-independent integer types always have the same size, regardless of what platform you use. In general, arithmetic operations on integers return a value of type Integerwhich is equivalent to the bit LongInt.
Operations return a value of type Int64 only when performed on one or more Int64 operands. Therefore, the following code produces incorrect results:. To get an Int64 return value in this situation, cast I as Int64 :. For more information, see Arithmetic Operators. Note: Some standard routines that take integer arguments truncate Int64 values to 32 bits.
A few routines cannot take Int64 values at all. When you increment the last value or decrement the first value of an integer type, the result wraps around the beginning or end of the range.
For example, the ShortInt type has the range If compiler range-checking is enabled, however, this code generates a runtime error. A string constant of length 1, such as 'A', can denote a character value. The predefined function Chr returns the character value for any integer in the range of WideChar ; for example, Chr 65 returns the letter A. AnsiChar and WideChar values, like integers, wrap around when decremented or incremented past the beginning or end of their range unless range-checking is enabled.
For example, after execution of the code:. Note: The AnsiChar type is not supported by the Delphi mobile compilers, but is used by the Delphi desktop compilers. Boolean is the preferred type. The others exist to provide compatibility with other languages and operating system libraries. A Boolean variable occupies one byte of memory, a ByteBool variable also occupies one byte, a WordBool variable occupies 2 bytes one wordand a LongBool variable occupies 4 bytes 2 words.
Boolean values are denoted by the predefined constants True and False. The following relationships hold:. If such a value appears in a context where a Boolean is expected, the compiler automatically converts any value of nonzero ordinality to True.
The previous remarks refer to the ordinality of Boolean values, not to the values themselves. In Delphi, Boolean expressions cannot be equated with integers or reals.As with any programming language, in Delphivariables are placeholders used to store values; they have names and data types.
The data type of a variable determines how the bits representing those values are stored in the computer's memory. When we have a variable that will contain some array of characters, we can declare it to be of type String. Delphi provides a healthy assortment of string operators, functions and procedures. Before assigning a String data type to a variable, we need to thoroughly understand Delphi's four string types. The first byte of this array stores the length of the string.
Since this was the main string type in Delphi 1 16 bit Delphithe only reason to use Short String is for backward compatibility. To create a ShortString type variable we use:. Since this is usually wasteful - unlikely will your short string spread to the maximum length - second approach to using Short Strings is using subtypes of ShortString, whose maximum length is anywhere from 0 to Note: When we assign a value to a Short String variable, the string is truncated if it exceeds the maximum length for the type.
When we pass short strings to some Delphi's string manipulating routine, they are converted to and from long string. Long string in Delphi's help AnsiString represents a dynamically allocated string whose maximum length is limited only by available memory.
All bit Delphi versions use long strings by default. I recommend using long strings whenever you can. The string grows or shrinks as you assign new data to it. The following code. Since memory allocation is done by Delphi, we don't have to worry about garbage collection. When working with Long Ansi Strings Delphi uses reference counting.
This way string copying is actually faster for long strings than for short strings. Reference counting, by example:. To minimize copying when we pass strings to routines, Delphi uses copy-on-write technique. Wide strings consist of bit Unicode characters.
Unicode stores each character in the character set in 2 bytes instead of 1. Some national languages use ideographic characters, which require more than the characters supported by ANSI. With bit notation we can represent 65, different characters.Delphi Basics.
Standard components. Delphi data types. For those new to computer programming, data and code go hand in hand. You cannot write a program of any real value without lines of code, or without data.
A Word Processor program has logic that takes what the user types and stores it in data. It also uses data to control how it stores and formats what the user types and clicks.
Data is stored in the memory of the computer when the program runs it can also be stored in a file, but that is another matter beyond the scope of this tutorial. Each memory 'slot' is identified by a name that the programmer chooses. For example LineTotal might be used to name a memory slot that holds the total number of lines in a Word Processor document. The program can freely read from and write to this memory slot.
This kind of data is called a Variable. It can contain data such as a number or text. Sometimes, we may have data that we do not want to change. For example, the maximum number of lines that the Word Processor can handle.
When we give a name to such data, we also give it its permanent value. These are called constants.
Like many modern languages, Delphi provides a rich variety of ways of storing data. We'll cover the basic, simple types here. Before we do, we'll show how to define a variable to Delphi:. We'll show later exactly where this var section fits into your program. Notice that the variable definitions are indented - this makes the code easier to read - indicating that they are part of the var block.
Each variable starts with the name you choose, followed by a : and then the variable type. As with all Delphi statements, a ; terminates the line. As you can see, you can define multiple variables in one line if they are of the same type. It is very important that the name you choose for each variable is unique, otherwise Delphi will not know how to identify which you are referring to.
It must also be different from the Delphi language keywords. Don't worry, you don't need to come up with an unusually creative name such as Me and Ro Jewelry and others in the fashion industry for each of your variables.
Unique in this case simply means the only occurrence. You'll know when you have got it right when Delphi compiles your code OK by hitting Ctrl-F9 to compile.
Delphi is not sensitive about the case lower or upper of your names. Delphi provides many different data types for storing numbers.
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Your choice depends on the data you want to handle.When working with Byte Arrays sooner or later the question of visualization raises. Here it makes sense to output the individual bytes in hexadecimal form as a string. In this tip, I want to show you a function that does just that. The function goes through the byte array byte by byte and converts each byte value into the corresponding hexadecimal value:. On the one hand, the function can be called only with a byte array or on the other hand optionally with a separator, which is written between the individual bytes for better readability.
In this example, we first create a byte array that is 3 bytes long and then fill it with some values. Then we use our function to output these values. In this context, it is also interesting how to load or save a byte array from respectively to a file. The author has not added a short description to his profile yet. Show Profile Message. Please note: The contributions published on askingbox. They are not verified by independents and do not necessarily reflect the opinion of askingbox.
Participate Login Register Ask Question. Info User Top Donate Deutsch. About About us Contact Advertise here.Arrays allow us to refer to a series of variables by the same name and to use a number an index to call out individual elements in that series.
Elements of the array are values that are all of the same type string, integer, record, custom object. Suppose we are writing a program that lets a user enter some values e. We would choose to store the information in a list.Harmony Bytes 1: Do you know DeFi?
We could call this list Appointmentsand each number might be stored as Appointments, Appointments, and so on. Given this declaration, Appointments denotes the fourth integer value in Appointments. The number in the brackets is called the index. The following code can be used to set all elements in the Appointments array to 0.
Sometimes we need to keep track of related information in an array. For example, to keep track of each pixel on your computer screen, you need to refer to its X and Y coordinates using a multidimensional array to store the values. With Delphi, we can declare arrays of multiple dimensions. For example, the following statement declares a two-dimensional 7 by 24 array:. To compute the number of elements in a multidimensional array, multiply the number of elements in each index.
To retrieve the value from the cell in the third row and seventh column we would use: DayHour[3,7] or DayHour. The following code can be used to set all elements in the DayHour array to 0. You may not know exactly how large to make an array. You may want to have the capability of changing the size of the array at runtime. A dynamic array declares its type, but not its size. The actual size of a dynamic array can be changed at runtime by the use of the SetLength procedure.
The declaration does not allocate memory for Students. To create the array in memory, we call SetLength procedure. For example, given the declaration above. Dynamic arrays are always integer-indexed, always starting from 0 to one less than their size in elements. Very often, your program doesn't know at compile time how many elements will be needed; that number will not be known until runtime. With dynamic arrays, you can allocate only as much storage as is required at a given time.
In other words, the size of dynamic arrays can be changed at runtime, which is one of the key advantages of dynamic arrays. The next example creates an array of integer values and then calls the Copy function to resize the array. The SetLength function creates a larger or smaller array and copies the existing values to the new array. The Low and High functions ensure you access every array element without looking back in your code for the correct lower and upper index values.
Share Flipboard Email. Zarko Gajic.You must be logged to download. Click here to login. No, I'd like to download without make the donation. Graduated in System Analysis, in business development for over six years, where he worked in companies of various segments such as financial, commercial, parking, etc.
He is currently a third-party developer analyst Navy of Brazi String to Byte and Byte to String: Delphi. Save this as uFrmPrincipal. Wesley Yamazack Batista teste Graduated in System Analysis, in business development for over six years, where he worked in companies of various segments such as financial, commercial, parking, etc.
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See the prices for this post in Mr. Subscribe for this package! Click here to login If you don't have a MrBool registration, click here to register free. You need have acess to enable the download links.Use ReadBuffer to read Count bytes from the stream into a buffer in cases where the number of bytes is known and fixed, for example when reading in structures.
ReadBuffer is used internally for loading from a stream and copying from a stream. ReadBuffer calls Read to do the actual reading. If Count bytes cannot be read from the stream, an EReadError exception is raised. Collapse All. Reads bytes from the stream into Buffer.
Use this project to create files of any encoding. This example requires two text edits and a combobox. Create Edit1. Create Edit2. GetPreamble; LFileStream. Free; end ; end ; procedure TForm1. Unicode' ; Add 'TEncoding. Default' ; Add 'TEncoding. The list box should contain one or more items. When the form becomes visible, click on the button and the contents of the list box will be transferred to a stream and then to the rich edit control.
Create; ListBox1. Lines, nil ; TempStream. Free; end ; procedure TForm1. Size - Stream. EndUpdate; end ; end ; procedure TForm1.
Add 'Apples' ; ListBox1. Add 'Oranges' ; ListBox1.
Simple Types (Delphi)
Add 'Pears' ; end. See Also. Copyright C Embarcadero Technologies, Inc. All Rights Reserved. What do you think about this topic? Send feedback!