I think you want to distinguish between numbers and letters:

Use isalpha () and isdigit () to determine whether a character is a number or a letter.

Please refer to the resources for specific usage.

In addition, the char type itself stores the ascii code of characters, defined as int or plastic, and defined as char or character type.

Such as input 65,

65 if stored in int variable, and' a' if stored in char variable.