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Asked: 2026-06-12T12:40:08+00:00

I am working on porting an application to 64-bit on Linux platform. The application

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I am working on porting an application to 64-bit on Linux platform. The application is currently supported on Linux, Windows, Mac 32-bit and Windows 64-bit. One of the issues we are frequently encountering is the usage of long for int and vice versa. This wasn’t a problem till now since long and int are interchangeable (both are 4 bytes) in the platforms the application is currently supported on. The codebase being a huge one, with lots of legacy code with #defines for many data types, makes it cumbersome to search all usage of long and replace appropriately with int.

  1. As a short term solution, is there a way to make GCC use 4 bytes instead of 8 for ‘long’?
  2. If it has, what are issues that we might face? If not, is there an easier way to fix the long and int problem?
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1 Answer

  1. Editorial Team

    1. No. On Linux x86_64 the ABI specifies that long is a 8 byte type (LP64). In fact, most if not all 64-bit Unix systems (including 64-bit OS X, AFAIK) are LP64 so this is nothing specific to Linux.

    2. Beyond fixing your code, no.

    If you need a portable integer type which is large enough to store a pointer value, use intptr_t or uintptr_t (but usually wanting to store a pointer value into an integer means that you’re doing something wrong, so think twice!). For an integer type which is capable of representing the difference between two pointers, use ptrdiff_t. For sizes of objects, use size_t.

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