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This article introduces the relevant knowledge of "how to understand Python conditional statements". In the operation process of actual cases, many people will encounter such difficulties. Next, let Xiaobian lead you to learn how to deal with these situations! I hope you can read carefully and learn something!

01 if conditional statement

The if statement is used to check whether a condition is true. If true, execute the program in the if statement; otherwise, skip the if statement and execute the following content. The format of the if statement is as follows.

if(expression): Statement 1 else: statement 2

If the Boolean value of the expression is true, execute statement 1; otherwise, execute statement 2. The else clause can be omitted, and the parentheses around the expression can also be omitted.

Before we talk about if statements, let's look at console input functions in Python. In C, user input is captured using scanf() and getchar(), while the Java language's System.in package provides methods for console input. Python also provides a similar function--input(), which captures the user's raw input and converts it into a string. The input() function is declared as follows.

input([prompt]) -> string

Parameter prompt is a prompt text for input in the console, prompting the user to input, and the return value is a character string. If the input is a number and the return is a string, then int() needs to be called to convert the string and number types before use. The following code illustrates the conversion of string and numeric types.

x = input("x:") x = int(x) x = x + 1

If the expression x = x + 1 is evaluated without calling int() to convert a string to a number, the following error will be displayed.

TypeError: Can't convert 'int' object to str implicitly

The following code demonstrates the flow of execution of an if statement:

1#Execute the program inside the if statement 2a = input("a:") 3a = int(a) 4b = input("b:") 5b = int(b) 6if(a > b): 7 print (a, " > ", b)

[Code Description]

Line 2 defines the variable a.

Line 3 converts the user-entered a to an int.

Line 4 defines the variable b.

Line 5 converts the b entered by the user to an int.

Line 6 determines the size of variables a and b.

For line 7, assuming a=2, b=1, the output result is 2>1.

If the condition in the if statement is not met, the program skips the if statement and executes the rest.

1#Skip if sentence 2a = input("a:") 3a = int(a) 4b = input("b:") 5b = int(b) 6if(a > b): 7 print (a, " > ", b) 8print (a, "

", b) 8else: 9 print (a, " < ", b)

[Code Description]

Assuming a=1 and b=2, the value of variable a in line 6 is less than the value of variable b. Therefore, the program jumps to the else clause.

Line 9 Output: 1

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