3 Pseudocode, Flowcharts and Python Goadrich（3伪代码,流程图和Python Goadrich）.pdfVIP

3 Pseudocode, Flowcharts and Python In Chapter 2, we learned how to store information in the computer and the rules governing the manipulation of numbers and logical values. Now we will look at how to organize those rules to create simple programs. 3.1 Sequential Order Programs are similar to books. In a book, you start reading from the top of the page and continue to the end of the page. In English, each line of text in the book contains information that is read from left to right. Likewise, we write programs for the computer to read in this order from left to right. Remember assignment statements from the previous chapter, a = 3 means that a stores the value of 3, not that 3 is a. Now that we read each line appropriately, we will always start reading from the top line of our program and continuing until the last line in the program. The programs that we will look at in this chapter are all executed in sequential order. We will start with the first line and then continue to the next line. This sequence control structure can be represented with pseudocode, flowcharts, and Python code. 3.2 Pseudocode First we will look at outlining a program using pseudocode. Pseudocode is a language very close to English that allows us to represent a program concisely. The only thing you need is a statement to show where you are starting and where you are ending a program. We will be using the word Start for the start point and the word End to show the finish point. Each program will contain statements to accomplish our goal; this will satisfy step 3 from Chapter 1. 9 3.3 Flowcharts A more visual way to see the behavior of a program is a flowchart which is appealing to the visual learner. A fl