A string expression concatenates two or more strings to create a new string. The operands can be variables, literal strings enclosed in double-quotes, or functions that return strings.
For example, the string expression "Hello, " & "world." concatenates the strings "Hello, "and "world." The result is "Hello, world."
Use the Substring function to extract part of a string. When using Substring, the first parameter is the string. The second parameter, the Index, is the number of the first character to extract. The third parameter is the number of characters to include after the Index. For example, Substring("Hello", 4, 2) returns "lo". If the third parameter is omitted, the entire string from the Index to the end of the string is returned.
Numbers used in string expressions are automatically converted to strings when used with string operators. For example, "value_"&(index+1) evaluates the numerical expression index+1, after which the resulting number is concatenated to the end of the string value_.