Python基础–详细记录Fourth_Chapter

Python基础–详细记录Fourth_Chapter

1、条件语句

1.1 条件表达式

例子：

1.2 多分支结构

1.3 选择嵌套结构

2、循环语句

2.1 while循环

2.2 for循环

2.3 可迭代对象

2.4 嵌套循环

2.5 break、continue和else语句

2.6 循环代码优化

举例：

其他优化手段：

3、并行迭代

names = ["zc","ws","fw"]
ages=[18,20,25,32]
jobs = ["老师","程序员","医生"]
for name,age,job in zip(names,ages,jobs):
    print(name,age,job)

4、推导式

4.1 列表推导式

s = [x**2 for x in range(10) if x%2==0]
print(s)
print([x**2 for x in range(10) if x%2==0])
y =[]
for i in range(10):
    if i%2==0:
        y.append(i**2)
print(y)
s1 = [(a+1,b*2) for a in range(10) for b in range(10)]
print(s1)
s2 = [x for x in "abcde"]
print(s2)

4.2 字典推导式

a = "where is and when is "
b = {c:a.count(c) for c in a}
print(b)

4.3 集合推导式

s3 = {x**2 for x in range(10)}
print(s3)

4.4 生成器推导式

s4 = (x for x in range(10) if x%2==0)
print(s4)
print(list(s4))

s4 = (x for x in range(10) if x%2==0)
for i in s4:
    print(i)