For example, int a；; ; Represents the statement "plastic variable a";

int a，b，c； There are three integer variables a, b and C.

But int a,; b； c； The computer will look at the first sentence like this: there is an integer variable A. The second sentence B. The third sentence C. "

Because B and C appear separately, the computer can't recognize what they are, so the computer has an error.

Then you can write it like this

int a；

int b；

int

Or int a；; ; int b； int c；

Then the computer can recognize it.

You just need to remember that commas are the separators of variables, and semicolons indicate the end of statements.