What's the Real Difference Between `int` and `long` in C ?

Understanding the Difference Between int and long in C

The distinction between int and long data types in C often raises questions. While it may seem straightforward that they both occupy 4 bytes and share the same value range, this assumption is not entirely accurate.

The key difference is that their sizes and value ranges are implementation-dependent. This means that different platforms or compilers may define these types differently.

For example, on Windows systems, both int and long have a size of 4 bytes and a value range from -2,147,483,648 to 2,147,483,647 (2^31). On other systems, this may not hold true.

On Alpha systems, for instance, a long is 64 bits wide, while an int remains 32 bits. This means that the value range for long is significantly larger on Alpha systems.

The Intel C compiler provides a comprehensive guide to the rules for variable platform sizes:

OS	Architecture	Size
Windows	IA-32	4 bytes
Windows	Intel 64	4 bytes
Windows	IA-64	4 bytes
Linux	IA-32	4 bytes
Linux	Intel 64	8 bytes
Linux	IA-64	8 bytes
Mac OS X	IA-32	4 bytes
Mac OS X	Intel 64	8 bytes

Therefore, it is important to consider the platform or compiler being used when choosing between int and long. They should not be used interchangeably without considering the implementation-specific characteristics.

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