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Background.
The concept of type is one of the fundamental concepts of any programming language. Objects (constants, variables, functions, expressions), which operates the program; refer to a certain type of. Type - a set of values, which can take objects from the program, and a set of operations allowed on these values. For example, the values 1 and 2 refer to an integer, you can add, multiply, and perform other arithmetic operations. The values of the "system" and "PASCAL" are linguistic in nature; they are, of course, its own set of allowed operations.
In most widely used languages may be used only - strictly defined, pre-known types such as integer, real, literal. PASCAL along with the standard types available in other high-level languages allows the programmer to form your own types.
All valid in the Pascal types are divided into two main groups: scalar and structured. Scalar types are divided into standard and described by the user. Structured types are based on scalar types and may contain various combinations of them.
The standard scalar types.
The standard scalar data types include integer, byte, real, literal, and Boolean types.
Integer type defines all the integers in the range -32768 to 32767. To describe an integer type is the standard identifier integer.
Format: <identifier. . .>: Integer;
To place a memory variable of type integer takes 2 bytes. Typically, this type of variables used in arithmetic expressions, for organizing and indexing counter array. The customer has to make sure that the intermediate results of arithmetic expressions did not come from a range of -32 768. . . 32767.
Variable of type byte is one byte in memory, i.e., in comparison with an integer type memory saved twice. Use byte type may be advisable if it is known that the value does not exceed 255. In arithmetic and logical expressions is acceptable mix of types and byte integer. All that will be discussed below on the type of integer, refers to the type byte.
A variable of type real is in memory of 6 bytes. |
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