Problems with 64bit integer constant

[Jeff Gilchrist]

I have tried searching the newsgroup along with the GCC site and could
not find what I think is probably a simple solution.

I am using a 64bit unsigned long long integer and can manipulate 64bits
within the variable but I cannot assign a 64bit constant to it.

With my simple test program:

int main()
{
unsigned long long test;

test = 18446744073709551606;
test = 0xFFFFFFFFFFFFFFF6;
}

I get the following errors with gcc v3.3.x and 3.4:

test.cpp:7: warning: this decimal constant is unsigned only in ISO C90
test.cpp:7: error: integer constant is too large for "long" type
test.cpp:8: error: integer constant is too large for "long" type


I have also tried using variations with no success:
test = (unsigned long long)18446744073709551606;

There must be a way to do this, and it is probably just something
simple that I am overlooking. Can anyone help?

Thanks.

 

[John Valko]

test = 18446744073709551606;
test = 0xFFFFFFFFFFFFFFF6;

Add the suffix "LLU" to the constants and it should work for you.

-- John

 

[Victor Bazarov]

I have tried searching the newsgroup along with the GCC site and could
not find what I think is probably a simple solution.

I am using a 64bit unsigned long long integer and can manipulate 64bits
within the variable but I cannot assign a 64bit constant to it.

With my simple test program:

int main()
{
unsigned long long test;

There is no 'long long' data type in C++. There is in C99. Perhaps you
need to post your question to the C newsgroup (comp.lang.c)?

test = 18446744073709551606;
test = 0xFFFFFFFFFFFFFFF6;
}

I get the following errors with gcc v3.3.x and 3.4:

test.cpp:7: warning: this decimal constant is unsigned only in ISO C90

The constant has a signed type _unless_ it has the U suffix. Try

test = 18446744073709551606U; // for "native" unsigned int

or

test = 18446744073709551606UL; // for "native" unsigned long

The constant is really too big to fit into a signed integer.

test.cpp:7: error: integer constant is too large for "long" type
test.cpp:8: error: integer constant is too large for "long" type


I have also tried using variations with no success:
test = (unsigned long long)18446744073709551606;

There must be a way to do this, and it is probably just something
simple that I am overlooking. Can anyone help?

If your _C++_ compiler natively supports 64-bit numbers, then it would be
under 'unsigned long' type, and not 'unsigned long long'. Otherwise, this
is a wrong forum to ask about it. Try gnu.g++.help.

Victor

 

[Jeff Gilchrist]

There is no 'long long' data type in C++. There is in C99. Perhaps
you need to post your question to the C newsgroup (comp.lang.c)?

You are right of course. I sometimes forget which things are in the C
standard and which are in the C++ since most C++ compilers treat C code
as a substet of C++ and its hard to tell the difference.

For people with 32bit processors, how does one create a 64bit data type
in C++ if 'int' and 'long' are both treated as 32bit in the
compiler(s)?

Thanks,
Jeff.

 

[Jeff Gilchrist]

Add the suffix "LLU" to the constants and it should work for you.

Thanks John, works like a charm.

Much appreciated,
Jeff.

 

[Victor Bazarov]

[..]
For people with 32bit processors, how does one create a 64bit data type
in C++ if 'int' and 'long' are both treated as 32bit in the
compiler(s)?

Usually that's achieved by means of some language extensions. E.g., VC++
has '__int64' and 'unsigned __int64' that can be used. Constants of these
types have non-standard suffixes 'i64' and 'ui64'.

V

 

[Rolf Magnus]

[..]
For people with 32bit processors, how does one create a 64bit data type
in C++ if 'int' and 'long' are both treated as 32bit in the
compiler(s)?

Usually that's achieved by means of some language extensions. E.g., VC++
has '__int64' and 'unsigned __int64' that can be used.

And gcc has 'long long' and 'unsigned long long'.

Constants of these types have non-standard suffixes 'i64' and 'ui64'.

What do you mean by "non-standard suffixes"?

 

[Victor Bazarov]

Victor Bazarov wrote:

[..]
For people with 32bit processors, how does one create a 64bit data type
in C++ if 'int' and 'long' are both treated as 32bit in the
compiler(s)?

Usually that's achieved by means of some language extensions. E.g., VC++
has '__int64' and 'unsigned __int64' that can be used.

And gcc has 'long long' and 'unsigned long long'.

Constants of these types have non-standard suffixes 'i64' and 'ui64'.

What do you mean by "non-standard suffixes"?

AFAIK, there are no standard suffixes 'i64' and 'ui64'. There are 'L',
'U', 'UL', 'F'. And by "constants" I actually meant "literals". My bad.