What is the '-->' operator in C/C++?

Solution 1

--> is not an operator. It is in fact two separate operators, -- and >.

The code in the condition decrements x, while returning x's original (not decremented) value, and then compares the original value with 0 using the > operator.

To better understand, the statement could be written as follows:

while( (x--) > 0 )

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Solution 2

Or for something completely different... x slides to 0.

while (x --\
            \
             \
              \
               > 0)
     printf("%d ", x);

Not so mathematical, but... every picture paints a thousand words...

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Solution 3

That's a very complicated operator, so even ISO/IEC JTC1 (Joint Technical Committee 1) placed its description in two different parts of the C++ Standard.

Joking aside, they are two different operators: -- and > described respectively in §5.2.6/2 and §5.9 of the C++03 Standard.

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Solution 4

x can go to zero even faster in the opposite direction in C++:

int x = 10;
while( 0 <---- x )
{
printf(“%d ”, x);
}

8 6 4 2

You can control speed with an arrow!

int x = 100;
while( 0 <-------------------- x )
{
printf(“%d ”, x);
}

90 80 70 60 50 40 30 20 10

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Solution 5

It's equivalent to

while (x-- > 0)

x-- (post decrement) is equivalent to x = x-1 (but returning the original value of x), so the code transforms to:

while(x > 0) {
    x = x-1;
    // logic
}
x--;   // The post decrement done when x <= 0

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