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FPDoc Onlineexperiment

TFPSListCompareFunc procedure type

In unit fgl

Compare list items callback signature.

Declaration

pascal
TFPSListCompareFunc = function(Key1: Pointer; Key2: Pointer): Integer
 of object

Arguments

Key1

First key value.

Key2

Second key value.

Function result

Is key1 less than key2.

Description

TFPSListCompareFunc is used in the Sort method to compare 2 elements. The list passes 2 pointers to the actual items to the compare function. The result of this function determines how the pointers will be sorted:

  • If the result of this function is negative, the first key (key1) is assumed to be 'less' than the second key (key2) and will be moved before the second in the list.
  • If the function result is positive, the first key (key1) pointer is assumed to be 'greater than' the second key (key2)and will be moved after the second in the list.
  • if the function result is zero, the keys are assumed to be 'equal' and no moving will take place.

See also

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.