How to get rid of integer overflow warning?

Question

In my C++ code I have an expression where I multiply unsigned long integer to an int to assign the result to unsigned long int. I am getting a warning as 'overflowed returned value'. I tried to cast the int to unsigned long but it did not help. Any suggestions...

The expression is something like this-

uint64_t size = 0;
uint64_t value = getvalue();
int pageSize= getPageSize();
size = value*(uint64_t)pageSize;

If overflow is intended and you just want to suppress the warning, try to use unsigned int instead of plain int. — n. m. could be an AI
– n. m. could be an AI, Commented Aug 31, 2011 at 9:10
overflow is not intended and the function which return plain int can not be changed to return unsigned long neither the return value 'size'. — polapts
– polapts, Commented Aug 31, 2011 at 9:12
Which compiler and version are we talking about here? This doesn't repro with gcc/g++ 4.5.2. And I tried with -Wall, -Wextra, and -pedantic and variations of -Wstrict-overflow=N — selbie
– selbie, Commented Aug 31, 2011 at 9:21

ur. · Accepted Answer · 2011-08-31 09:25:55Z

1

The following should do the job:

size = value*(uint64_t)(unsigned int)pageSize;

answered Aug 31, 2011 at 9:25

ur.

2,9471 gold badge18 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Matthieu M. · Accepted Answer · 2011-08-31 09:38:18Z

0

Your tool probably has a way to set an exception for this line of code.

If the tool is truly clever, this is the only way, for there really is a risk of overflow here (as an int may not accomodate 2^64-1).

answered Aug 31, 2011 at 9:38

Matthieu M.

303k58 gold badges495 silver badges754 bronze badges

Collectives™ on Stack Overflow

How to get rid of integer overflow warning?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related