for语句

Python for循环可以遍历任何序列的项目，如一个列表或者一个字符串

for的实现逻辑

for song in songs:
# song = '爱转角' => song[0]
print("正在播放{}".format(song))
# 把索引 + 1
# song = 晴天 ==》 song[1]

实例1：
for i in "python":
    print(i,end="")    #end="" 表示不换行打印
#打印结果：python

实例2.通过列表方式：
list = ["banana","apple","orage","lenmo"]
for fruit in list:
    print("fruit:{}".format(fruit))
#打印结果：fruit:banana
#fruit:apple
#fruit:orage
#fruit:lenmo

列表可以使用 for 循环
元组可以使用 for 循环
字典使用 for 循环，取到的默认是所有 key, 如果想取到所有value：
for i in dic.values():
如果想取到所有的值：
for e in dic.items():

实例1：
dic = {
    
    "yello":"banana","red":"apple"}
for i in dic:
    print(i)                ===> 打印结果：yello  red

实例2：
dic = {
    
    "yello":"banana","red":"apple"}
for i in dic.values():
    print(i)               ===> 打印结果：banana  apple

实例3：
dic = {
    
    "yello":"banana","red":"apple"}
for i in dic.items():
    print(i)               ===> 打印结果：('yello', 'banana')   ('red', 'apple')
 
实例4：
dic = {
    
    "yello":"banana","red":"apple"}
for i in dic:
    print(dic[i])               ===> 打印结果：banana  apple

实例5：
for key ,value in dic.items():
    print("key:{} , value:{}".format(key,value))    ===> 打印结果：key:yello , value:banana    key:red , value:apple

for 的嵌套

实例1：
list = ["banana","apple","orage","lenmo"]
dict = ["color","fruit"]
for i in list:
    for e in dict:
        print("list :{} , dict :{}".format(list,dict))
'''
打印结果：
list :banana , dict :color
list :banana , dict :fruit
list :apple , dict :color
list :apple , dict :fruit
list :orage , dict :color
list :orage , dict :fruit
list :lenmo , dict :color
list :lenmo , dict :fruit
会先执行完 dict 里面的所有元素，在返回执行list里面的下一个元素
'''

实例2：
python = [['yello','banana'],['red','apple'],['orange','orange']]
for i in python:
    print(i)
    for e in i:
        print(e)
'''
打印结果：
['yello', 'banana']
yello
banana
['red', 'apple']
red
apple
['orange', 'orange']
orange
orange
'''

for 常见面试题 ：乘法表

方法1：
for i in range(1,10):
    for e in range(1,i+1):
        print("{} * {} = {}".format(i, e, i * e), end='\t')
    print()


方法2：
for i in range(1,10):
    for j in range(1, 10):
        if j <= i:
            print("{} * {} = {}".format(i, j, i*j), end='\t')
    print()