How to make a program flowchart?

A program flowchart is a diagram that describes, using prescribed symbols, the various operations or judgments required in a dedicated program. This type of flowchart focuses on illustrating the logic and processing sequence of the program, specifically describing the logic and steps involved in solving microcomputer problems. When the program has more loops and transfer statements, the structure of the program will be more complex, causing difficulties in program design and reading. The program flow chart draws the program flow in the form of a diagram, which is a graphical representation of the algorithm, and has the characteristics of intuitive, clear and easier to understand. [2]

Program flow chart consists of processing boxes, judgment boxes, start and stop boxes, connection points, flow lines, comment boxes, etc., and combined with the corresponding algorithms, constituting the entire program flow chart.

The processing box has the function of processing; the judgment box (diamond box) has the function of conditional judgment, there is an entrance and two exits; the start and stop box indicates the beginning or end of the program; the connection point can be connected to the flow line; the flow line (indicates the path and direction of the process; the comment box is for the operation of the flow chart of some boxes to do the necessary supplementary explanation. [3]

The three basic structures of a program flowchart

Any complex algorithm can be composed of three basic structures: sequential, selective (branching), and cyclic, and therefore, an algorithm is constructed using only these three basic structures as the "building blocks," and adhering to the specifications of the three basic structures. Therefore, when constructing an algorithm, only these three basic structures are used as the "building units", and the specifications of the three basic structures are observed. Precisely because the entire algorithm is composed of three basic structures, as if built with modules, so the structure is clear, easy to verify the correctness, easy to correct errors, this method, is the structured approach. Programming that follows this approach is structured programming. Accordingly, you can draw a flowchart of any algorithm as long as you specify how to draw a flowchart of the three basic structures. [4]

(1) Sequential Structure

The sequential structure is a simple linear structure in which the boxes are executed in sequence. The basic shape of its flowchart is shown in the figure, where the statements are executed in the order ABC.[1]

(2) Selection (Branching) Structure

This structure is a judgment of a given condition, where the contents of different boxes are executed respectively when the condition is true or false. There are two basic shapes. [1]

(3) Loop structures

Loop structures have two basic shapes: while-type loops and do - while type loops. a. while-type loops: the execution sequence is: when the condition is true, execute A repeatedly, once the condition is false, jump out of the loop and execute the statement immediately after the loop. b. do - while type loops: the execution sequence is: First execute A, then judge the condition, when the condition is true, keep executing A in a loop, once the condition is false, end the loop and execute the next statement immediately after the loop.