Little question about postfix and prefix

[firebird]

I thought this code:

{           int	myInt;
             myInt = 5;
             printf( "myInt++ ---> %d\n\n++myInt ---> %d", myInt++, ++myInt);
}

will yield:

"myInt++ ---> 5

++myInt ---> 7"

but it actually gave:

"myInt++ ---> 6

++myInt ---> 7"

with a warning: operation on 'myInt' may be undefined.

Can some one help me out? I'm so confused by the result and the warning message.

[laserlight]

Read this C FAQ on expressions.

[cpjust]

Changing a variable more than once in a single statement is undefined.

[firebird]

Thank you guys very much.