How do I convert a positive number to negative in Delphi?

问题

How do I convert a positive Integer to a negative with Delphi? I know you could use ABS(int) to convert a negative to a positive, but I need it to convert positive to negative.

回答1:

from what I know there is no function for that. you can make

if yourvariable > 0 then
    yourvariable := -yourvariable;

回答2:

If you want to be absolutely sure to get a negative result (or zero), use

number := -abs(number)

回答3:

Ehhh... Too late but number := number * -1; would work too, but this change the symbol of any number, negative to positive and backwards... To ensure a negative value go with @Mef Answer

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EDIT: even later, but number := 0 - number; would work too... This just reverses the symbol as well

回答4:

Let n be your number and the formula for n-(n*2) = -n

来源：https://stackoverflow.com/questions/9968707/how-do-i-convert-a-positive-number-to-negative-in-delphi