True allergies to cow's milk are relatively uncommon. Only 2 to 3 percent of children are allergic to milk, according to the AAP, and almost all of them outgrow it by age 3. (Learn the difference between a milk allergy and lactose intolerance .).
The underscore [ _ ] (also called underline, underbar, low line, or low dash) is a character that originally appeared on the typewriter and was primarily used to underline words.
The first character of an identifier name must be a nondigit (that is, the first character must be an underscore or an uppercase or lowercase letter). ANSI allows six significant characters in an external identifier's name and 31 for names of internal (within a function) identifiers.