1.int represents an integer: int func () represents that the function func returns an integer value, int I；; I is an integer variable.

2 . void func()； It means that the function func returns a null value, that is, it does not return.

3.main is the main program entry function in C language. Must be defined, because the program needs to have a main function to execute.

4. & means and. If a&; B refers to the AND operation of binary values of A and B .. & There are three rules. 1。 1 = 1;

0 & amp 1 = 0 ; 0 & amp0 = 0; That is, only all 1 are 1. Such as 5&; 4 =( 10 1)； (100) = 100 = 4. You can learn more about the decimal system.

5.% refers to the remainder (or modulus). 5%3=2. It means 5 divided by 3 and 2. That is, 5 modulo 3 equals 2.

I hope it helps.