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Using the basic Icon types

In an Icon program, types are defined only by their run-time usage. So far in this tutorial we have encountered these types:

• integer: As in the constants 0 and 1.
• real: For constants written with a decimal point (e.g., ``3.0''), and the result returned by the square root function ``sqrt()''.
• string: For constants written inside double quotes, like the first argument to ``write()'' in this statement:

          write ( "The sum of 1 to 5 is ", sum );

• procedure: The ``main()'' and other procedures in our sample programs have this type.

Icon has a number of other useful built-in types. You can also create your own types.