# It uses two structures called the dowhile and the

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Unformatted text preview: ly illustrate the logic of these structures. Their corresponding pseudocodes are also given in these figures. The IF... THEN... ELSE construct says that if the condition is true, then do Process 1, else (if the condition is not true) do Process 2. Thus, in this case either Process 1 or Process 2 will be executed depending on whether the specified condition is true or false. However, if we do not want to choose between the two processes and if we simply want to decide if a process is to be performed or not, then the IF...THEN structure is used. The IF... THEN structure says that if the condition is true, then do Process 1 and if it is not true then skip over Process 1. The CASE structure is a multiple-way selection logic structure that allows to choose between more than two control paths in a program logic. It allows the selection of one of any number of statements or statement groups. It is, therefore, a generalization of the one-way (IF...THEN) and two-way (IF...THEN...ELSE) selection logic structures. In fact, one-way and two-way selection logic structures can be built with a multiple-way selection logic structure. The CASE statement says that if the value of Type is equal to Type-1 then execute Process 1, if it is equal to Type-2 then execute Process 2, if it is equal to Type-3 then execute Process 3, and so on. IF Condition Yes THEN Process 1 ELSE Process 2 ENDIF (a) Flowchart In all these structures, Process 1, Process 2, Process 3, etc. can actually be one or more processes. They are not limited to a single process. ENDIF is used to indicate the end of the IF,... THEN and IF... THEN.. .ELSE decision structures and ENDCASE is used to indicate the end of the CASE structure. Iteration (or Looping) Logic Iteration logic is used to produce loops in program logic when one or more instructions may be executed several times depending on some condition. It uses two structures called the DO...WHILE and the REPEAT...UNTIL. They are illustrated by flowcharts in Figure 11.18 and Figure 11.19 respectively. Their corresponding pseudocodes are also g...
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