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PHP PHP Basics Unit Converter Arithmetic Operators

Ty Mckenzie
Ty Mckenzie
3,465 Points

Why does var_dump(a$--); not subtract 1?

$a = 5;

$b = 10;

$a = $a + 1;

var_dump($a); <---- = int(6)

$a++;

var_dump($a); <---- = int(7)

$a--;

var_dump($a); <---- = int(6)

var_dump($a--); <---- = int(6) Why isn't this 5?

var_dump($a); <---- = int(5)

var_dump(--$a); <---- = int(4)

var_dump($a); <---- = int(4)

Console

int(6)
int(7)
int(6)
int(6)
int(5)
int(4)
int(4)

1 Answer

Steven Parker
Steven Parker
229,921 Points

It does subtract, the issue is just when.

When you write --$a, that's the predecrement operator. It subtracts one before returning the value.

But $a-- is the postdecrement operator, it subtracts one after returning the value.

For more details, see the PHP documentation.

Ty Mckenzie
Ty Mckenzie
3,465 Points

Ahhh of course. Thanks!