python控制流：用for循环造数据

一.for循环

1.range循环

for n in range (8):
    print(n)

2.列表循环

li=[21,"sdf",4,"ht"]
for x in li:
    print(x)

3.字典循环

dic1={"name":"lie","age":18}      //字典
for p in dic1.values():         //循环字典值
    print(p)
for p in dic1.keys():           //循环字典键
    print(p)
for q in dic1.items():         //获取键值对
    print(q)               //循环键值对
for a,b in dic1.items():
    print(a,b)        //循环键和值
for y in dic1.items():       //循环键值对
    for s in y:           //循环键值对得到键和值
        print(s)
for x,y in dic1.items():
    if x=="age":
        if y>17:
            print(dic1)
            print(x,y)
    print(x,y)

4.利用for循环造数据

请求体里的json里包含多个相同的json，如图：嵌套循环得到数据。c包含3个a，每个a里包含2个b。

data_text=[]                 #放置a的list
for x in range(3):           #循环3次
    data_text1 = []          #放置b的list
    for y in range(2):       #循环2次
        c={
            "orderList":data_text
        }
        b = {
            "orderLineNumber": "test_1" + str(x + 1)+ str(y + 1),
            "orderNumber": "test_d" + str(x + 1)
        }
        a = {
            "orderNumber": "test_d" + str(x + 1),
            "orderLineList": data_text1
        }
        data_text1.append(b)         #内层循环把b添加到data_text1数组里
    data_text.append(a)              #外层循环把a添加到data_text数组里
filename="2_5.txt"
with open(filename,"a",encoding="utf-8") as  fd:
    fd.write(json.dumps(c,ensure_ascii=False))
    fd.write("\n")
    fd.close()

二.if语句

1.一个等于符号是赋值，两个等于符号才是逻辑运算符；

2.Python是一种类自然语言，所以写法和英文语法很像；

3.条件体后面必须有执行体，如果不执行，也必须用pass占个位置

 

a=21
print(type(a))
if a in ["dfs",21,98,2.1]:
    if type(a) is int:
        pass
    elif isinstance(a,str):        #如果a是str
        print(a)
    else:
        print("error")