It was developed in 1970. Niklaus Virget as a language that provides strict typing and intuitive syntax. He was named after French mathematics, physics and philosopher Blaze Pascal.
One of the objectives of creating a language Pascal Niklaus Wirth considered student learning to structural programming. Until now, Pascal is deservedly considered one of best languages For initial training programming. Its modern modifications, such as Object Pascal, are widely used in industrial programming (Delphi).
Blaise Pascal
| Released in 1995 as a continuation of the Turbo Pascal environment of the Delphi programming system has become one of the best media fast creation Applications. Delphi introduced a number of successful object-oriented extensions into the tongue; The updated language was called Object Pascal. Starting from the Delphi 7.0 version, the Delphi Object Pascal language began to be called just Delphi, however, the old name is used often. Latest version Environments - Delphi Xe. |  Wednesday Delphi 7. |
The most famous free implementations of the Pascal language is Free Pascal. In addition to the openness of the source code, its main advantage is multiplatform, as well as the support of various dialects of Pascal. Based on FreePascal, a free Lazarus multiplatform medium has been created, similar to the Delphi environment. However, poor and non-decades that are not changing in the FREE Pascal integrated medium, a little compatible with modern interfaces desktops operating systems, more and more pushing the students, incorrectly forming the idea that Pascal is an outdated language.
On the other hand, the Delphi environment has become becoming increasingly cumbersome and user-friendly programming. There is no free version Delphi even for academic use. These factors led to the practically complete disappearance of Delphi from the scope of education, and for the Lazarus environment, despite its free, such cases are single.
Finally, the appearance of Java i.net platforms, including a powerful programming language and powerful standard libraries Weakened the position of the Delphi language. For learning, programming has become more commonly used such languages \u200b\u200bas Java, C, C ++, C #, Visual Basic., Python, Haskell.
One of the bright events related to the development of the Language Pascal was the appearance of a language and compiler of the Oxygene of the company Remobjects, which the creators were deservedly called the modern Pascal of the 21st century. Oxygene can generate code for various platforms, including under platform.NET and Java. Its main disadvantage is the lack of a free compiler and medium for educational purposes. In addition, Oxygene is quite different from the canonical language Pascal (methods of classes instead of procedures and functions), which reflects its purely professional orientation.
Language and programming system website It is intended to change the current situation and return the language of Pascal to the former attractiveness of both learning and for professional programming, by changing it to the power of the platform.net.
Choose the lessons you are interested in in Pascal:
Pascal language is very often used in education. The name is the English word Pascal - the name of the famous mathematics and philosopher from France - Blaze Pascal, but it is not connected with the programming ideology.
History of Pascal language
Pascal - This is a programming language related to the structural paradigm. Pascal was designed to teach schoolchildren and students in the 70s of the XX century.
Pascal language was created by the scientist Niklaus Virget from Switzerland, which was a specialist in the field of computer science and computer sciences, as well as a well-known theorist in the development of programming languages.
Initially, Pascal was created by processing algol-60. Somewhere in 1968, the project was prepared, and the developers have begun to create a translator intended for use on the CDC 6400 computing machine. In 1971, its official description was announced (Wirth N. The Programming Language Pascal // Acta Informatica. - 1971. Vol1 .N1.).
Nicklaus Wirth himself in his writings indicates that the purpose of creating it is "building a small and efficient language that promotes a good programming style using structural programming and structured data".
A particularly popular period of distribution of Pascal was 1972-1975. At that time, the characteristics of the Pascal language and its capabilities allowed him not only to complete universal recognition, but also made it a basic means for teaching the "Programming" discipline and to develop programs. In 1975, a whole Association of Pascal users appears. But later the language was criticized. The restrictions on the main designs of the Pascal language were too strict, and it did not like this much to users. In 1977, a group on developing the Pascal standard appears. The leader of the group was A.Eddiman (A.M.Addyman). On December 1, 1983, the International Language Standard was created, the name of ISO 7185.
Studying Pascal through the lessons presented on the site will allow to reveal the advantages and disadvantages of Pascal, to figure out how the structure of the program is arranged, study the main operators. Examples of programs and ready-made tasks with a solution are designed for both beginners for learning Pascal and for students and schoolchildren.
We wish you good luck!
On the unstacked worldwide Internet, you can find a lot of programs in the language "Pascal", but it is much more difficult to figure out, according to which principle they work and how they are arranged. Let's study the basics of programming together!
Algorithmic language: basic concepts
In conversational speech, we use the main units: symbols, and entire proposal. The algorithmic language also has a similar structure, only its components are called differently. We are talking about elementary structures, expressions and operators. All these units form a hierarchical structure, since each subsequent element is formed from the previous one.
The symbols of the algorithmic language are indivisible atoms used for writing code.
Elementary structures are minimal units that have their own meaning.
Classical language expressions are formed from the two above-mentioned units and set the rules for finding the necessary value.
The operator is responsible for a description of a specific conversion, which is mandatory for the correct execution of the program. There may be several of them if necessary - the program must perform a challenging operation. In such situations, they are combined into the block or a composite operator.
Language "Pascal"
Exists a large number of "Pascal" (for beginners there are separate benefits) is one of them. Its alphabet consists of numbers, letters and special characters. Here are their list:
- 26 Latin capital and;
- underscore;
- ten digits;
- limiters;
- operations;
- specifiers;
- reserved system (service) words.
In addition to the elements listed above, a "space" must be used to the basic set, which cannot be used inside the design of reserved expressions and dual characters.
Elemental language designs
"Pascal" for beginners includes lines, numbers and names.
The numbers used in the code of the programming language under consideration are usually written in decimal system. They can be both valid and integers that are customary to mention without a decimal point. If the number is positive, then its sign can be omitted.
"Pascal" is an algorithmic programming language in which the strings are a sequence of symbols closed in apostrophes. If you need to use the apostrophe itself, then this symbol is worth mentioning twice.
The name is a sequence that begins with the letter and may contain in its composition. The identifiers are customary to call tags, types, constants, functions, procedures, variables, objects and even modules. Forming identifiers you can use the underscore. The name can have a lot of characters, but the compiler will read only the first 63 signs. "Pascal", the description of which may seem so difficult, not so terrible, so do not rush to scare and closure the browser page!
As a language identifiers, it is prohibited to use the standard names of the constants, procedures, types, files, functions, as well as service expressions.
Improve the visibility of the code will help spaces, but it is worth remembering that they cannot be separated by names and numbers in the middle.
Syntax of the algorithmic language
Each line must end with a comma point in the program written in the language we are covered ("Pascal"). Informatics teaches this schoolchildren and students, and you can realize these rules themselves!
A semicolon (;) is a conditional signal that speaks of the end of the current line and the need to go to a new one. But the exception can be service teams: const, var, begin and others.
The END operator closes the program, so after it is necessarily a point. Sometimes the code may contain several attachments, then the beginning and end of the block will be separated by a semicolon.
To assign a variable of a certain value before the familiar, you need to put the colon. For example, you go to set n \u003d 13, and in the code it will look like n: \u003d 13.
If you learn these rules, you can quickly learn how to write a program code without syntactic errors.
Classic Language Operators "Pascal"
Program the repeated fragments of the future application code and carry out any actions with it using different ways. But the "Pascal" language uses various operators for this. All of them we will not be able to consider, so we will understand only with some.
For example, using the selection operator, you can choose one of the alternative paths of the program. The parameter in this case is the expression of the sequence type. But there is one nuance: this selection key cannot belong to the String or Real type.
There are still appropriation operators, conditional, composite and empty, as well as the mass of other useful investments. Knowledge of only some of them allows you to write code with excellent functionality. Operators should not be abused, because their large quantity makes the program complex in debugging the compiler, confusing and very severe to perceive foreign people.
Application operator
This expression has the form of a colon and sign "equal." It is used to assign a specific variable value. It is important to remember that the type of expression and variable must be coincided if they do not relate to a whole and valid type, respectively. Only in such a situation there will be a direct transformation.
Composite operators
"Pascal" is a programming language that uses sequences of arbitrary software operators enclosed in special brackets. We are talking about the composite structures limited by the words Begin and End. This is an important tool of the algorithmic language by which the ability to write code appears using a structural methodology.
Pascal operators entering into part of the composite design can be completely different, because there are no restrictions. The depth of nesting can also be different.
Conditional programming language operator
This component provides the ability to check the specified condition during the program and perform an action depending on the results of its passage. Thus, the conditional command is one of the means of forming branches in the process of performing calculations.
Structurally as follows:
If<условие> Then.<оператор1> ELSE.<оператор2>.
In this expression, ELSE, THEN and IF are reserved words, the condition - logical expression With arbitrary content, and operators - any commands of the programming language used.
Software structure
Title, sections of operators and descriptions are key components of applications written in such as "Pascal". Computer science allows you to fully explore these elements and learn how to use them correctly.
The title typically contains the name of the code. For example, Program MyFirst.
The Descriptions section may include connected libraries, modules, labels, constants, types, variables, head descriptions and procedures.
The module description section contains inside the names of the connected libraries and starts with the reserved word uses. It must be the first among all other descriptions. The names of the modules should be separated from each other commas.
You can put a label to any program code operator whose name should be mentioned in the appropriate description section.
Premature description of the constant allows you to prescribe their names in the code instead of digital or letter values.
In the descriptions of the variables used, you should specify all types that will be involved: "VAR C, A, R: INTEGER; K, L, M: CHAR; H1, H2: Boolean;".
Do not forget that "Pascal" is a programming language that requires mandatory preliminary description All components involved in the program.
The code code must end with a point.
Examples of programs
"Pascal" is an elementary language, and after studying the information described above, you can proceed directly to writing code.
Let's make the application bring the phrase "IT IS My First Program!"
Examples of programs on "Pascal" is very important to understand, so try to do it right now.
Begin.
Writeln (IT IT My First Program! ");
End.
That's so simple!
Look at a more complex code with which you can find the roots pay attention to the principle of formation of computational expressions.
We hope they were useful for you.
You are in the section of materials on the programming on Pascal. Before you start programming, you need to clarify some of the concepts that we need at the beginning. After all, it is impossible to program so much. We cannot record the program with words - the computer besides zeros and units do not understand anything else. To do this, a special symbolism has been created in Pascal - Pascal's language, a set of reserved words that cannot be used in their programs anywhere else, except for its intended purpose. We list the basic concepts that we need at the beginning:
✎ 1) Program - in English "Program", writes at the very beginning of the code, after which the name of the program of the Latin and a comma point is. For example: program Summa; - Program called Summa. But this part of the code, called the heading of the program, can not write - it is present only for clarity and shows what task is solves this program. Here we used the word "code" - the text of the program is called.
✎ 2) Integer - in English means "integer" (or simply "integer") and in Pascal is used to designate 32-bit (8 bytes) integers with a range from the range [-2147483648, 2147483647]. What do these big numbers mean, we will then discern.✎ 3) REAL - from the English "real", "real", "real", "valid". In the Pascal language, this term refers to real numbers from the range [-1.8 ∙ 10 308, 1.8 ∙ 10 308]. These are very large numbers, but significant digits are displayed 15 - 16. By the way, the data types of Integer and Real in the PascalaBC.net programming environment are always automatically highlighted in blue.
✎ 4) Const is an analogue of the English. "Constant", meaning "constant", "Constant". In Pascal, this is a value that cannot be changed. Written like this:
This entry should be perceived as it is written: the number n is 12, s is 5, "PI" is 3.14 (as in mathematics, only instead of the comma in Pascal, the point is used). In the last line, we used a double slash (two oblique features), after which the text goes, "the comments are written in Pascal, and their program does not perceive. Everything that begins the double slash and until the end of the line is a comment that is written to explain to the program and is always highlighted by another color (in PascalaBC.NET it is green, this type of comment is not used in Turbo Pascal). There is another comment type - this (text enclosed in curly brackets, as well as here, which also stands out in green). This view of the comment may act a few rows in a row - from the beginning of the bracket and before its closure, and everything that is in the middle of such a design, the compiler does not perceive as the code and simply skips.
In fact, the recording format const. A little harder. According to the rules, we had to write:
|
After declaring each value, its type is specified, and then the value is assigned. But the previous post is also correct, since the Pascal compiler is configured so that it automatically defines the type of constant. But this cannot be said about the following type of numbers - variables.
5) VAR - comes from the English. "VARIABLE" ("variable", or "changeable"), which in Pascal means the value that during the program can change its value. Written like this:
As can be seen from the recording, the sign "\u003d" is not here - the variables of the same type (through the comma) are recalculated and only the type is indicated after the colon. Variables n, m (integer) and q, r, t (real) in the program can change values \u200b\u200bwithin Integer and Real, respectively. Another note: the description of the variables is always standing after the description of the constants (permanent) - first there is a construct design, and then var.
✎ 6) Begin - Translated from English means "start" and Pascal means the beginning of the main program in which commands (operators) are recorded. After the word begin. The point with the comma is not put.
✎ 7) END - in English. "End", and in Pascal language means the same (end of the program). After the last word end. Always worth a point. We allocated the word "last" because the use of the design begin - End. Perhaps in one case: these are the so-called operator brackets that are used to combine several operations under one operator. But about this later. Thus, the main program will look like this:
|
Here, operators in the body of the program are different commands to the compiler.
✎ 8) Write - in English means "writing". This operator displays the text placed in it, so it is called - the output operator. The text placed in it is highlighted in blue and is written as follows:
Write ( "This text is displayed on the screen.");
The message in brackets and quotes will be shown in the console window (simply in brackets without quotes cannot be). After completing this operator, we will see on the screen:
this text is displayed on the screen.
In this form, the WRITE operator is used when it is necessary to show the hint, explanation, comment, etc. and from if you need to withdraw even a numeric value, say, S \u003d 50 kV. m, then the format is used:
Write (, S);
As a result, we obtain the result on the screen:
Square is equal to: S \u003d 50
And if necessary, output units, it is necessary to insert text in quotes after s again:
Write ( "Square is equal to: s \u003d", S, "sq.m");
After executing the last output operator, we get output to the screen:
The size of the square is: S \u003d 50 sq.m
✎ 9) Writeln is the same as Write, but after executing the cursor will be translated to the next string.
✎ 10) Read - translated from English means "read", so READ is called the reader operator, or data entry. It is written as read (n), which means the need to enter the value of n, where n is any number, or text, or another type of variable. For example, if you need to enter a person's age, which is 32 years old, we can write this way:
In the first line of this code, the program displays the question " What is your age?"And translates the cursor to the next line (ending ln); In the second line, we deposit "year \u003d" (at the beginning of the space); Next, we see the READLN operator (YEAR) meaning the need to introduce the age of the Year (number 32); Finally, we bring the message "My age", "32" and "year. "Alternately. It is necessary to closely monitor spaces. As a result of the execution of this code, we will receive a message:
What is your age?
YEAR \u003d 32.
My age is 32 years old
✎ 11) readln - the same as read, only with the translation to new string. Indeed, in the example above after the introduction of the number of YEAR we are only in next line We write: " My age is 32 years old».
It is still all. On the next page We will write the first program, and in programming on Pascal it will be our
Among the many programming languages \u200b\u200bintended for training exactly programming skills, there is one that is highlighted. The tongue of Pascal, named after the French scientist XVII century Blaze Pascal, was developed in the late 1960s. Scientists from Switzerland by Niklaus Virut, and not with the educational purpose, as this language is perceived now.
On the contrary, in those days, scientists have tried different programming languages \u200b\u200bfor practical application. And later, this scientist later created two more programming languages \u200b\u200b- Oberon and modules, which, however, did not receive distribution among specialists. To be accurate, then 1968 was created the first version of the Pascal language (based on Algola), and 1970 - the first compiler.
Pascal feature is its structural orientation - any program here can be described in the form of unification of individual structural elements, or blocks, in a single whole. This is the so-called structural programming that changed the linear programming is the simplest organization of writing programs when the commands of the processor are recorded one after another, without any structure.
The idea of \u200b\u200bstructural programming turned out to be both relevant at that time and very fruitful, because not for all tasks it is possible to write a program by specifying the sequence of simple commands without disconnecting the latter into separate blocks. Indeed, only if there is a certain structure of the program, you can judge an effective problem solving algorithm.
This became clearly clear after about 1970, Professor Hoar published two articles: "Axiomatic Programming Programming For Computing Machines" and "On Structural Data Organization", in which an attempt is made to compile the correctness of the compilation of algorithms of programs from a mathematical point of view. Just the programming language Pascal and is the first of the languages \u200b\u200bin which all required tools To verify the effectiveness of the written programs.
Another distinctive feature of Pascal is its strict typing of data, among which there was a new previously used type - listed. The strict typing factor made a reputation to paste as a disciplining language leining the programmer to logical thinking.
In Pascal, unbound program code is allowed (unlike the then Cobol and Fortran languages), that is, there is an arbitrarily much of the presence of empty lines, which is convenient when formatting when writing comments. The program on the Pascal can be written at least one line - it will work evenly, if written in accordance with the rules.
But with the distribution of this programming language it turned out that it lacks many elements familiar to us - the construction of a local variable, dynamic arrays, the possibility of using machine language And others. The most famous expression of this shortage of that time is the article of Kernigan "Why Pascal is not my favorite programming language."
One of the reasons for such discontent with a Pascal of that time was the inability to write a program compiled with several parts, since it simply did not provide for mechanisms. But Niklaus Wirth with colleagues in the subsequent releases of Pascal eliminated all these shortcomings, following all programming principles.
