Character string function.

Some Character string functions are introduced.


a=val("36")
 String type data "36" is changed to numerical data.

s$=str$(58)
 Numerical type data 58 is changed to string data.

s$=mid$("abcdefg",3,4)
 In string "abcdefg", to take out four characters from 3rd character, and return.
 ("cdef" is substituted 's$')