. A string is represented as a character.

Copy is a string function in the format of copy ('string', starting character, several characters).

For example, the return value of copy('abcd', 2, 1) is B, which means that the second letter of the string abcd begins with a letter.

Strtoint is to convert a string into an integer.

A: = stroint (copy (field by name ('menu item')). Asstring， 1， 1))；

The meaning of this sentence is

The current value of the "menu item" field, starting from the first character, takes a character, and the result is changed from character type to plastic, and assigned to the variable A.

Above.