On a 32-bit computer, all 32-bit programs store their files in C:\Program Files, and the system-wide library location is C:\System32.

On a 64-bit computer, 64-bit programs store their files in C:\Program Files, and the system-wide C:\Windows\System32 folder contains 64-bit libraries. 32-bit programs store their files in C:\Program Files (x86), and the system-wide folder is C:\Windows\SysWOW64.

This is definitely counterintuitive. Despite the “32” in the name, the System32 folder contains 64-bit libraries. And, despite the 64 in the name, the SysWOW64 folder contains 32-bit libraries—at least on 64-bit versions of Windows.

On est bien chez Microsoft, quoi ^_^

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