Detailed code sharing about Python process control

1.while statement

Conditional loop control statement. Generally it needs to be used together with break, otherwise it will enter an infinite loop.

Format: [ while ：

                                                                                                                                                                                                                            

##Conditional control of process branches, generally used with elif and else.

x=int(input('请输入一个数字：'))while x>0:    print('正数')    break

For a simple if else statement, you can use ternary operation (ternary operation) to express

x=int(input('请输入一个数字：'))
if x<0:
    print(&#39;负数&#39;)
elif x==0:
    print(&#39;零&#39;)
else :
    print(&#39;正数&#39;)

3.for statement

Loop Control statements can be used to traverse an object and are used together with in.

Format: [for in

4.range() function

Number sequence An iterator, when you iterate over it, is an object that returns consecutive items in the desired sequence, but to save space, it doesn't actually construct a list.

Format: range(stop) gives the end value, the start value defaults to 0, and the interval is 1. Range (Start, Stop) gives the start value and end value, and the interval is 1.

Range (Start, STOP, STEP) gives the start value and end value, and the interval is STEP value.

x=['a','b','c','d']for i in x :             
 # i 位置的字符，只要不是关键字，可以随意用字符代表
    print(i)

5.break and continue statements, and else statements in loops

1) break

statements and
Similar in C

, used to jump out of the nearest level for or while loop.

for i in range(3):          #运行结果为0，1，2
    print(i)for i in range(0,5):       #运行结果为0，1，2，3，4
    print(i)for i in range(-2,10,2): #运行结果为-2，0，2，4，6，8
    print(i)

2) continue statement

indicates that the loop continues to execute the next iteration

:

while True:    
print('hello')    
break

3) else in the loopFor example, in the continue example, there is a for-else statement. The else statement will be executed after the loop jumps out, but break will not execute else when the loop jumps out, so Else can be used to handle some exceptions in the loop.

for x in range(1, 4):
        print(x, 'for语句')
        continue
        print(x, 'continue语句后')
else:
        print(x, 'else语句')
 
#运行结果
for语句
for语句
for语句
else语句

6.pass statement

The pass statement does nothing. It is used in situations where syntactically necessary statements are required, but the program does nothing. It is usually used to create minimally structured classes.

On the other hand, pass can be used as a placeholder for a function or control body when creating new code. Allows you to think on a more abstract level.

for x in range(1, 4):
        print(x)
else:
        print(x)

#运行结果
2
3

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