Like C and Java, there are conditional selection and looping statements in Python, similar in style to C and Java, but there are some differences in writing and usage. Let's take a look at it today.
I. Conditional SELECTION statement
The key word for a conditional selection statement in Python is: If, elif, else three. The basic form is as follows:
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If condition:
Block
Elif Condition:
Block
...
Else
Block
Where the elif and else statement blocks are optional. The spoke statement executes only if condition is true for if and elif, and the Else branch is executed only if the IF and all elif condition are false. Note the difference between conditional selection statements in Python and C, where condition must be enclosed in parentheses, not in Python, but be aware that there is a colon behind the condition.
Here's an example of grading grades.：
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Score=input ()
If score<60:
Print "D"
Elif score<80:
Print "C"
Elif score<90:
Print "B"
Else
Print "A"
Two. Circular statements
Like the C language, Python provides a for loop and a while loop (there is no do in Python). While loop) two kinds. But the for loop usage in Python is very different from the C language (similar to the for loop usage in Java and C #), while loop usage is roughly similar to the C language.
The basic form for a For loop is as follows:
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For variable in list:
Block
For example, calculate from 1 plus to 100 and:
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Sum=0
for Var in range (1,101):
Sum+=var
Print sum
Range () is a built-in function that can generate a list of numbers in a range. For example, range (1,6) generates a list of [1,2,3,4,5], and range (8) generates a list of [0,1,2,3,4,5,6,7].
Of course there can be nested loops, such as having a list of ' list=[', ' England ', ' America ', to traverse the output of each letter.
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list=[' ', ' England ', ' America '
For I in range (len (list)):
Word=list[i]
For j in range (Len (word)):
Print Word[j]
The built-in function len () can be used not only to calculate the length of a string, but also to find the number of members in a list or collection.
Here's a look at the basic form of the while loop:
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The loop is executed only if condition is true. Once the condition is false, the loop terminates.
As an example:
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count=2
While count>0:
Print "I love python!"
Count=count-1
If you want to terminate the loop in the statement block process, you can use break or continue. The break is out of the loop, and the continue is out of the loop.
Copy Code code as follows:
Count=5
While True:
Print "I love python!"
Count=count-1
If count==2:
Break
Copy Code code as follows:
Count=5
While count>0:
Count=count-1
If count==3:
Continue
Print "I love python!"
The basic usage of conditional statements and circular statements is so much more so. If you are interested, you'd better do your own practice on the machine.
