How to detect Overflow of Long type

Question

0.00/5 (No votes)

See more:

Hi guys,

Can any one help me with detecting an overflow with data type long. I C++.
i dont want to go for the arithmetic way that if b < (b+C) then over flow occurred.
Is there any Method or falg that will detect the overflow for me.?

With Regards,
Saurabh

Posted 18-Jun-12 1:37am

Saurabh.abhyankar

Add a Solution

3 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

JackDingler · Answer 1 · 2012-06-18T06:51:00

Idle63 posted a good answer for an alternative to a 'long' data type.

But a more direct answer is that, there is no method or flag, built into the C language that will detect this overflow for you.

The C language was designed to operate as close to the metal as possible. Widespread bounds validation for primitive types, would severely impact code performance, and is left as an exercise for the software engineer. Further, customization of bounds checking, requires additional variables to compare against, for underflow and overflow. This would add additional complexity to primitive data types.

Vitaly Tomilov · Answer 2 · 2012-06-18T15:03:00

Solution 3

1. If you understand assembler, then you can use operands JO and JNO to jump when overflow flag is set or not, accordingly. This would be the universal answer on x86 platform.

2. If you do not understand assembler, then just use safe types like Safe Integer - see them used in MSDN.

Posted 18-Jun-12 15:03pm

Vitaly Tomilov

idle63 · Answer 3 · 2012-06-18T02:11:00

Solution 1

You can use SafeInt. http://msdn.microsoft.com/en-us/library/dd570023(VS.100).aspx[^]

But probably it perfromance goes down.
Regards

Posted 18-Jun-12 2:11am

idle63

Comments

JackDingler 18-Jun-12 12:46pm

Good answer. and of course performance will be effected, much like the test b < (b+C), which is likely built into the SafeInt template in some form.

[no name] 18-Jun-12 14:52pm

Thx. Yes I would also prefer "test b < (b+C)".
Regards.