Judgment, cycle--day2 study notes

#Define a variable just to use its value later

#Programming is all dealing with memory

name='Zhang San'   

print(name)

#If there are single quotes in the variable, double quotes should be used, for example: name="let's go"

#If there are double quotation marks in the variable, single quotation marks should be used, for example: name='Zhang San looks "very handsome"!'

#If there are single quotes and double quotes in the variable, use triple quotes, for example: content = "'let's go,"lucy" '''

age = 10 #int type

name = 'Xiaobai' #string type string

score = 53.36 float, float

Built-in function: type #View variable type

print(type(age))

1. Conditional judgment    if else

For example: determine age

age = input( ' Please enter your age: ' )      # The input value accepted by input is of string type 

age = int(age)     # Type coercion, converted to Int type

if age<18:

　　print ( ' Minor ' )

else:

　　print ( ' Adult ' )

View Code

For example: Judgment of excellent, good, pass

score = input( ' Please enter your score: ' )

score = int(score)

if score >=90:

　　print ( ' excellent ' )

elif score >=75 and score<90:

　　print ( ' good ' )

elif score >=60 and score<75:

　　print ( ' pass ' )

else:

　　print ( ' Failed ' )

View Code

practise:

#generates a number 10

#Enter a number, if the input is small, the prompt is small; if the input is large, it will prompt him that the input is large

import random

num = random.randint (1,10 )

for i in rang(5):    #Guess 5 times 

　　new_num = input( ' Please enter the number you want: ' )

　　new_num = int(new_num)

　　if new_num>num:

　　　　print ( ' input is too large ' )

　　elif new_num <num:

　　　　print ( ' input is too small ' )

　　else:

　　　　print ( ' Congratulations on guessing correctly ' )

View Code

2. Loop (or iteration, traversal)

#for

#while must have a counter

#do one thing repeatedly

Example: while loop

count = 0 #define the counter

while count<10:

　　print('Hello world')

　　count = count + 1   #There must be a counter, and the counter must be increased, otherwise it will be an infinite loop

#loop body, when the loop is repeated, the things in the loop body are executed repeatedly

Circular exercise:

#7 Chances to Guess the Number

import random

num = random.randint (1,100 )

count = 0

while count < 7:

　　guess = input( ' Please enter the number you want to guess: ' )

　　guess = int(guess)

　　if guess<num:

　　　　print ( ' big guess ' )
　　elif guess > num:

　　　　print ( ' Guess is too small ' )
　　else :

　　　　print ( ' Congratulations, you guessed it right ' )
　　　　break     #Guess it right, exit the loop   
　　count = count + 1

View Code

#loop body: when looping, the things in the loop body are repeatedly executed

#break When a break is encountered in the loop, the loop ends immediately, but whether the loop is finished

#continue If you encounter continue in the loop, then end the loop and continue to the next loop

while:....

else: the operation to be done after the normal end of the loop

for loop:

for i in range(4): # Loop 4 times, the for loop automatically adds 1 loop, no counter is needed, the default starts from 0

print (i)　　 #0,1,2,3

print（‘hello’）