To get a trial key
fill out the form below
Team License (standard version)
Enterprise License (extended version)
* By clicking this button you agree to our Privacy Policy statement

** This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Request our prices
New License
License Renewal
--Select currency--
USD
EUR
GBP
RUB
* By clicking this button you agree to our Privacy Policy statement

** This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
To get the licence for your open-source project, please fill out this form
* By clicking this button you agree to our Privacy Policy statement

** This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
To get the licence for your open-source project, please fill out this form
* By clicking this button you agree to our Privacy Policy statement

** This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
I am interested to try it on the platforms:
* By clicking this button you agree to our Privacy Policy statement

** This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Message submitted.

Your message has been sent. We will email you at


If you haven't received our response, please do the following:
check your Spam/Junk folder and click the "Not Spam" button for our message.
This way, you won't miss messages from our team in the future.

>
>
>
V694. The condition (ptr - const_value)…
Analyzer Diagnostics
General Analysis (C++)
General Analysis (C#)
General Analysis (Java)
Diagnosis of micro-optimizations (C++)
Diagnosis of 64-bit errors (Viva64, C++)
MISRA errors
AUTOSAR errors
Additional information
Contents

V694. The condition (ptr - const_value) is only false if the value of a pointer equals a magic constant.

May 16 2014

The analyzer has detected a very suspicious condition: a constant value is added to or subtracted from a pointer. The result is then compared to zero. Such code is very likely to contain a typo.

Take a look at the following example with addition:

int *p = ...;
if (p + 2)

This condition will be always true. The only case when the expression evaluates to 0 is when you deliberately write the magic number "-2" into the pointer.

The fixed code:

int *p = ...;
if (*p + 2)

Now let's examine an example with subtraction:

char *begin = ...;
char *end = ...;
....
const size_t ibegin = 1;
....
if (end - ibegin)

It is the variable 'begin' that should have been subtracted from the variable 'end'. Because of the poor variable naming, the programmer used by mistake the constant integer variable 'ibegin'.

The fixed code:

char *begin = ...;
char *end = ...;
....
if (end - begin)

Note. This warning is generated only when the pointer is "actual" - e.g. pointing to a memory area allocated through the "malloc()" function. If the analyzer does not know what the pointer equals to, it won't generate the warning in order to avoid unnecessary false positives. It does happen sometimes that programmers pass "magic numbers" in pointers and conditions of the (ptr - 5 == 0) pattern do make sense.

This diagnostic is classified as:

You can look at examples of errors detected by the V694 diagnostic.

This website uses cookies and other technology to provide you a more personalized experience. By continuing the view of our web-pages you accept the terms of using these files. If you don't want your personal data to be processed, please, leave this site.
Learn More →
Accept