How can I create multi-line preprocessor macros in C ?

Creating Multi-Line Preprocessor Macros in C

When working with complex code, multi-line preprocessor macros can prove invaluable in improving code readability and reusability. The standard way of defining a one-line macro is well-known:

<code class="cpp">#define sqr(X) (X*X)</code>

However, for more complex macros, it can be impractical to squeeze everything into a single line. This is where the line continuation escape character '' comes into play. By appending '' to the end of a macro line, you can continue the macro definition onto multiple lines:

<code class="cpp">#define someMacro(X) \
    class X : public otherClass \
    { \
         int foo; \
         void doFoo(); \
    };</code>

This multi-line macro can now be used just like any other single-line macro:

<code class="cpp">someMacro(MyClass);</code>

Note: It is crucial that the '' character appears as the last character on the line. Any whitespace or other characters after the '' will result in unexpected behavior and compilation errors.

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