Identifiers

Identifiers are short pieces of text that are used as:

• variables names

• function names

• function argument keywords

• class names

• module names

Unlike string literals they are not enclosed in quotation marks.

Identifiers are like string literals pieces of text but can be easily distinguished from each other

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The variable name to the left of the equal sign = is not enclosed in quotation marks.

To get a valid, working identifier a small set of rules has to be followed:

• It must not be one of the keywords

• It may contain

  • lowercase and uppercase letters a .. z and A .. Z

  • digits 0 .. 9 except as the first character

  • underscores _

Actually Python 3 allows some additional characters, so letters like ä, ö, ü, ß could also be used.

Valid identifiers (used as a variable names)

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Invalid identifiers

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Each of the variables in the statements above throw an error (and aborts running the program).
► Try to correct all of them, one statment after the other, and watch the error messages.