c - Macro argument with different results -

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so have been having rather 'unyielding' problem macro call in c program. macro used :

#define macro(x) x*x

and problem when

printf("%d",macro(3));

it displays 9 result (which correct). when pass 3 2+1 follows :

printf("%d",macro(2+1));

it strangely displays outcome of 5. can please have me informed why?

printf("%d",macro(2+1));

after preprocessing become

printf("%d",2+1*2+1);

since multiplication has high precidenece on addition, print 5;

to resolve issue have define macro follows

#define macro(x) (x)*(x)

Two