問59
頻出度★★☆
プログラムの処理手順を図式を用いて視覚的に表したものはどれか。
平成27年度 春期 ITパスポート試験 問59
This question's explanation and your answers so far.
解説
問 59
Incorrectア
A Gantt chart lists a project's activities (tasks) on the vertical axis and time (the schedule) on the horizontal axis, showing each activity as a horizontal bar running from its start date to its end date. What it represents is progress and schedule management information — “when, which task, and for how long” — not the processing steps inside a program. It is a diagram used in project management, so it is outside the scope of this question.
Incorrectイ
A data flow diagram (DFD) focuses on the data flowing through a business operation or system, and uses four symbols — source/sink, process, data store, and data flow — to show “where data flows from and to.” It is used in structured analysis to grasp the overall picture of a business operation, but it does not express the execution order of processing such as decisions and repetition. It shows “the flow of data,” not “the flow of processing steps,” and that is the decisive difference from a flowchart.
- ウ
正解 The correct answer is ウ, “Flowchart.” A flowchart expresses the processing steps of a program or system using fixed-shape symbols (diagram symbols) that stand for start/end, process, decision, input/output, and so on, connected by arrows (flow lines). By following the arrows from top to bottom you can see the order of processing; branches leaving a decision symbol (a diamond) show the different paths taken depending on a condition, and an arrow that loops back expresses repetition. In other words, it is a diagram that visualizes the processing steps themselves as sequence, selection, and repetition, which matches the question's “visually represents the processing steps of a program using a diagram” exactly. It is used when explaining an algorithm to someone else, or when organizing the flow of processing before coding.
Incorrectエ
A radar chart plots values on several evaluation axes that radiate out from a center point, then connects those points with lines so that you can look at the shape of the resulting polygon. It is a data presentation technique for comparing the balance among multiple items and the overall tendency (used in the seven QC tools and the like); it is not a diagram that represents processing steps such as chronological order or branching.
ここがポイント
- Flowchart (flow diagram) = a diagramming method that visualizes the processing steps of a program or algorithm as sequence, selection, and repetition, using prescribed symbols and arrows.
- Learn to tell apart diagrams with similar names: Gantt chart = schedule/progress management, DFD = the flow of data (business analysis), radar chart = comparing the balance of multiple items. Distinguish them by “what the diagram represents.”
用語