Sequence points

[Senthil]

Hi,

When standard states this
"
i = v[i++]; // the behavior is undefined
i = ++i + 1; // the behavior is undefined
"

Do both of the following code snippets produces undefined behaviour or
the second one alone.

int m = 2;
int answer = ++m * ++m + ++m * ++m;

or

int m = 2
m = ++m * ++m + ++m * ++m;

What are the sequence points inside these expressions?

Thanks,
Senthil

 

[Artie Gold]

Hi,

When standard states this
"
i = v[i++]; // the behavior is undefined
i = ++i + 1; // the behavior is undefined
"

Do both of the following code snippets produces undefined behaviour or
the second one alone.

int m = 2;
int answer = ++m * ++m + ++m * ++m;

or

int m = 2
m = ++m * ++m + ++m * ++m;

What are the sequence points inside these expressions?

Thanks,
Senthil

They both produce UB, as there *are* no sequence points in either
expression.

HTH,
--ag

 

[Pete Becker]

What are the sequence points inside these expressions?

There aren't any. There is a sequence point at the end of each one. The
behavior of both statements is undefined, because they modify the value
of m more than once without an intervening sequence point.

 

[Senthil]

Thanks Pete and Artie!!!

I read books and i read the standard..but i am still not able to
understand what a sequence point is ?


Greetings,
Senthil

 

[Jack Klein]

Thanks Pete and Artie!!!

I read books and i read the standard..but i am still not able to
understand what a sequence point is ?


Greetings,
Senthil

Sequence points:

1. The ';' at the end of a full expression.

2. The comma operator (but the commas that separate arguments in a
function call are NOT comma operators).

3. At the '?' in the ternary expression.

4. During a function call, after all the arguments are evaluated,
before the function begins executing.

5. When a function ends/returns or exits by throwing an exception.

6. At the evaluation of a && or || logical operator.

7. At the initialization of each base and member in a constructor
with an initialization list.

 

[Senthil]

Thanks a ton, Jack


-senthil