Putting as many parentheses as possible in macros

#define SQR(x) x*x

• The preprocessor replaces every occurrence of the form

  SQR(a)
  

by the replacement text

a*a

For example:

w = SQR(x) + 1;

z = SQR(w+1);

becomes

w = x*x + 1;

z = w+1*w+1;

This is 2w+1, not (w+1)2 as intended.

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