A conditional in the C preprocessor begins with a conditional directive: ‘#if’, ‘#ifdef’ or ‘#ifndef’.
| • Ifdef: | ||
| • If: | ||
| • Defined: | ||
| • Else: | ||
| • Elif: | ||
• __has_attribute: |
||
• __has_cpp_attribute: |
||
• __has_builtin: |
||
• __has_include: |
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Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-10.2.0/cpp/Conditional-Syntax.html