Int Size Question

[Immortal Nephi]

I always use unsigned int to do math calculation or algorithm. The
int size was either 16 bit or 32 bit on older machine and older C++
Compiler. Today, int size is either 32 bit or 64 bit. The int size
is not important to me when math calculation or algorithm in my C++
code is performed maximum 16 bit. It does have enough room to either
int 32 bit or int 64 bit without 16 bit overflow.

My C++ code can be ported to any C++ Compiler on depend of different
machines. If I choose int 64 bit to do math calculation or algorithm,
how do I tell C++ Compiler to use int 64 bit instead of int 32 bit
with the answer -- sizeof? I do not have to remodify int size in all
header files and source code files.

Same example, char is always 8 bit, but one machine may have 9 bit or
10 bit width. To create string array in memory, each element is
always 8 bit. If 9 bit or 10 bit width is detected, then I must
accommodate to put 9 bit or 10 bit string array into 16 bit string
array.

 

[Steve Wolter]

My C++ code can be ported to any C++ Compiler on depend of different
machines. If I choose int 64 bit to do math calculation or algorithm,
how do I tell C++ Compiler to use int 64 bit instead of int 32 bit
with the answer [...]

The stdint.h header offers integer types with guaranteed sizes.
For example, uint8_t is an integer type 8 bits wide and unsigned.

Regards, Steve

 

[Juha Nieminen]

My C++ code can be ported to any C++ Compiler on depend of different
machines. If I choose int 64 bit to do math calculation or algorithm,
how do I tell C++ Compiler to use int 64 bit instead of int 32 bit
with the answer [...]

The stdint.h header offers integer types with guaranteed sizes.
For example, uint8_t is an integer type 8 bits wide and unsigned.

Note that stdint.h was only standardized in C99, and consequently not
yet part of the official C++ standard. Many C++ compilers support it,
though.

 

[Alf P. Steinbach]

* Juha Nieminen:

My C++ code can be ported to any C++ Compiler on depend of different
machines. If I choose int 64 bit to do math calculation or algorithm,
how do I tell C++ Compiler to use int 64 bit instead of int 32 bit
with the answer [...]

The stdint.h header offers integer types with guaranteed sizes.
For example, uint8_t is an integer type 8 bits wide and unsigned.

Note that stdint.h was only standardized in C99, and consequently not
yet part of the official C++ standard. Many C++ compilers support it,
though.

There is equivalent functionality in Boost.


Cheers,

- Alf