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2.10.2 String Expressions (StringExpression)

Compared with integer expressions the structure of string expressions (strings) is easier. The reason for this is very simple: there exists only one operator that converts two strings into a new string, namely the concatenation operator + , which simply attaches one string to another.

The basic modules of StringExpression are

• string constants (StringConstant)
• symbolic string constants (StringConstantIdentifier)
• string variables (StringVar)
• string registers (StringReg)
• return values of string functions (StringFunctionCall)

Besides the general scopy function there exists a second, special way to get to substrings:

returns the i-th character of StringExpression, where i is of IntExpression, 0 i len(StringExpression) - 1. (As usual we start counting from 0.)

Example 29:

Suppose language to be a variable of type STRING with contents "Retina Definition Language".

language[0] + language[7] + language[18] "RDL"

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