c++ - C programming unary operator precedence -

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   #include <stdio.h>     int main()     {      int c=10,b;      b=++c+++c;      printf("%d",b);      return 0;     }

could please let me know,why throwing compilation error?

the gibberish tokenised as

++ c ++ + c

and parsed as

((++c)++) + c

this tries increment rvalue yielded ++c, isn't allowed. can increment lvalue (or class type, in c++).

even if allowed, give undefined behaviour: you'd have unsequenced modification , use of value of c.

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