When programming in Pascal, you must select the data types of the Pascal program. It is important for the programmer to understand that in order to run his program in RAM, a place is allocated for storing not only the commands, but also the data with which these commands work.
All data types in Pascal are divided into two groups: simple and structured. For each data typea certain number of bytes is allocated. Simple types include: integer types (byte, integer, etc.), real types (real, single, etc.), a logical type (boolean), a character type (char), an enumerated and an interval type. All of them, with the exception of real types, are ordinal types and are characterized by the fact that they have a limited ordered set of values. For example, a variable of type byte can take values in the range from 0 to 255 inclusive. Such data types in Pascal allow you to use the functions Pred (calculates the previous value) and Succ (calculates the next value), Low (calculates the smallest type value) and High (calculates the largest type value), Ord (calculates the serial number of the current value of the variable).A simple type variable has only one given value, i.e. single integer, fractional number or single character. Variables that have simple data types in Pascal should be described in the Var section (abbreviated from Variables - Variables).
A variable in a Pascal program is considered fully defined if it has a name (identifier), type, and initial value. The name of the variable is used when accessing it through any operator. The data type determines the range of representation (what values a variable can take), the operations in which it can participate, the amount of memory that is required to store the variable in RAM. Therefore, when solving the problem, one should be inclined to reduce the number of variables and rational selection of their types.. : (array), (set of), (string), (file), (record). type ( ).
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A file is the same array, but the number of elements in it can change as the program runs. A record is a collection of heterogeneous data.
By learning to apply data types in Pascal, you can implement quite complex and interesting tasks.