Pointer type in Delphi

First, let's talk about how pointer types are defined in Delphi:

Definition Syntax of pointer type

Type

<Pointer type identifier >=^ <base type>;

The type of the pointer pointing to a dynamic variable is identified by the base type after the ^ character, and the ^ symbol is the pointer type. In C ++, the * symbol is used to represent the pointer type.

Example

Type

Student = record // defines the record type, which is similar to the structure type in C ++.

Name: String [8];

Number: integer;

Sex: (B, G );

Age: integer;

End;

Per = ^ student; // per is a record type pointer Structure

VaR

P1, p2: Per; // P1, P2 is pointer type, and P1, P2 is a dynamic variable of record type

R: ^ char; // The R pointer variable is a dynamic variable pointing to the character type.

 

What does a pointer-type operation look like? Let's give a simple example.

Type

STR = string [255]; // you can specify a string of 255 characters.

PTR = ^ STR; // define the pointer type

VaR

S: STR; // s indicates static memory allocation.

P: PTR; // P indicates the dynamically allocated memory.

S: = 'hello ';

P ^: = 'hello'; // The ^ symbol indicates the access to the pointer variable. Of course we can also use this

S: = P ^; this is equivalent to the above line

Do you know you will?

What does P and P ^ mean?

P is a 4-byte pointer variable and is statically stored. It is the first address of the dynamic variable memory.

P ^ is a 256-byte string variable and is dynamically stored. The data it points to can be changed at will.

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Pointer type in Delphi