Therefore, the value range of the variable I is between -32767 and +32767.

Therefore, the number you use is beyond this range. Then you can use long int I；;

In this way, its value is greatly increased.

Integers are numbers without decimal points. If the decimal point is used, it cannot be defined by int. Flaod or double is required, where double is longer than the decimal place of flaod.

If you want to define a character type, you should use char.