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PRE01-EX2: Macro parameters cannot be individually parenthesized when concatenating tokens using the ## operator, converting macro parameters to strings using the # operator, or concatenating adjacent string literals. The following JOIN() macro concatenates both arguments to form a new token. The SHOW() macro converts the single argument into a string literal, which is then passed as a parameter to printf() and as a string and as a parameter to the %d specifier. For For example, if SHOW() is invoked as SHOW(66);, the macro would be expanded to printf("66" " = %d\n", 66);.
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