Is 'long' Really 64-bits on 64-bit Windows?

Understanding the Bit Size of 'long' on 64-bit Windows

Question:

Conlicting information suggests that 'long' may not be 64 bits on 64-bit Windows machines. Is this true, and what should programmers use instead?

Answer:

The answer lies in examining different integer size arrangements on 64-bit platforms:

ILP64 (Int, Long, Pointers Are 64-bit)

• All integer data types and pointers are 64 bits.

LP64 (Long, Pointers Are 64-bit)

• Long and pointer types are 64 bits.
• Int and other integer types remain 32 bits.

LLP64 (Long Long, Pointers Are 64-bit)

• This is the scheme used by Microsoft in 64-bit Windows.
• Long long and pointer types are 64 bits.
• Int and long remain 32 bits.

Implications for Windows:

On 64-bit Windows, 'long' is indeed 32 bits, unlike on other 64-bit platforms. Microsoft adopted the LLP64 scheme to ensure compatibility with existing 32-bit applications.

Recommendations:

To ensure platform-neutral code, use integer types from the header:

• int32_t for 32-bit integers
• int64_t for 64-bit integers
• uintptr_t for pointers

Be cautious when using system types (e.g., 'long') as they may vary across platforms. Only use intptr_t as the result of subtracting two uintptr_t values.

Conclusion:

The bit size of 'long' on 64-bit Windows is 32 bits, deviating from the LP64 scheme used by many other 64-bit systems. To avoid platform-specific complications, programmers should adopt platform-neutral integer types and carefully handle system types.

The above is the detailed content of Is 'long' Really 64-bits on 64-bit Windows?. For more information, please follow other related articles on the PHP Chinese website!