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L.C.P        Logic of Programs construction

The data structure at the program entry (F.L.E= logical input file)

We have previously seen how to express the data that must be obtained at the output of the program.
You will agree that it is necessary to add to the F.L.S a very simple table in order to indicate :


  - The necessary input data
  - Calculations to be carried out
  - The conditions of appearance of conditionned Sub-sets

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I agree with you, most of the time we do not make this table because we have it in mind, but as we are in full theory, this table (wherever it is!) Is indispensable.

Now that we know the set (defined in extension) of the data required at the entry of the program, and also in what form they are, we must define the structure of the set of data at the input of the program.

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It is from this structure that we deduce the structure of the program.

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In order to discover the structure of the input data (F.L.E : Logical Input File), we proceed as for the output data, starting from the set which is subdivided successively level by level. The only difference, but it's essential, comes from the fact that each set is subdivided, not because it is present a number of times different from 1, but when it is used a number of times different from 1 .

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The criterion of subdivision of the set of data at the input is as follows :

A data set is subdivided at the program input if it contains Sub-Sets used a number of times different from 1.

We will now examine all possible structures that may be encountered in a program. But be aware already, that whatever the complexity of a program, this one will be built using only two elementary structures :

The repetitive structure

The alternative structure

Well, let us begin the study of all these structures,

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