# Operators

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# Free Pascal operators

## Address operator

The address operator @ returns the start address of a variable, a procedure or a function. If the compiler switch is {$ T-}, the return value is an untyped pointer. If the compiler switch is {$ T +}, the return value is a typed pointer. The default setting for the compiler is {$ T-}.

## Assignment operator

The assignment operator assigns a value to a data field.

```
a := b; // b is assigned to a
```

## Relational operators

The following operations are possible:

- Integer and floating point data fields can be mixed on both sides of the operator.
- Short, ANSI and Widestring data fields can be mixed on both sides of the operator.

Operator | Meaning |
---|---|

= | equal |

<> | not equal |

< | less than |

> | greater than |

<= | less than or equal |

>= | greater or equal |

in | checks whether the element appears in a set of the same data type |

## Binary arithmetic operators

Operator | Meaning |
---|---|

+ | addition |

- | subtraction |

* | multiplication |

/ | division |

div | integer division (Calculates the integer value of how many times an integer is in another integer.) |

mod | modulo division (Computes the integer remainder of a division of two integers.) |

## Unary arithmetic operators

+ specifies that the value is positive

- specifies that the value is negative

Examples:

```
a := +7;
b := -3;
```

## Logical operators

Operator | Operation |
---|---|

not | Bitwise unary negation |

and | Bitwise and |

or | Bitwise or |

xor | Bitwise exclusive or |

shl | Bitwise shift to the left |

shr | Bitwise shift to the right |

<< | Bitwise shift to the left (corresponds with the operator shl) |

>> | Bitwise shift to the right (corresponds with the operator shr) |

Examples:

```
A shr 1 // corresponds to integer DIV 2 (only that it is faster)
// (only for integer data fields, the result is rounded down to an integer)
Not 1 // corresponds to -2
Not 0 // corresponds to -1
Not -1 // corresponds to 0
B shl 2 // corresponds to integer * 4 (only that it is faster)
// (only for integer data fields, the result is an integer)
1 or 2 // corresponds to 3
3 xor 1 // corresponds to 2
```

## Truth operators

Operator | Operation |
---|---|

not | logical negation (unary) |

and | logical and |

or | logical or |

xor | logical xor |

## String operators

Operator | Operation |
---|---|

+ | String concatenation (joins two strings together) |

## Set operators

Operator | Operation |
---|---|

+ | union |

- | difference set |

* | intersection |

>< | symmetrical difference |

<= | contains |

include | add an item to the set |

exclude | delete an item in the set |

in | checks if the item is in the set |

## Class Operators

Operator | Operation |
---|---|

is | checks whether the object is of a certain class |

as | performs a conditional type cast (conditional typecasting) |

## Pointer Operators

Operator | Operation | Operand type | Result type | Example |
---|---|---|---|---|

+ | pointer addition | character pointer, integer | character pointer | P + I |

- | pointer subtraction | character pointer, integer | character pointer | P - Q |

^ | pointer dereference | pointer | basic type of pointer | P^ |

= | equal | pointer | boolean | P = Q |

<> | not equal | pointer | boolean | P <> Q |

## The priority of the operators

There is a rigid sequence for processing the operators.

Operators | Priority | Category |
---|---|---|

Not @ | first (highest) | Unary operators |

* / div mod and shl shr as << >> | second | Multiplication operators |

+ - or xor | third | Addition operators |

= <> < > <= >= in is | fourth (lowest) | Relational operators |