一.python内置函数
1.id()返回对象的内存地址
a = 1 print (id(a)) print (id(1))
2.int()用于将数据类型转换为整型
a = "1" b = 2 print (int(a) + b)
3.str()用于将数据类型转换为字符串
age = 18 name = "zhengying" print (name + " age is " + str(age) + " years old")
4.len()返回对象(字符、列表、元组、字典、集合等)长度或项目个数
- int型不能使用len()函数
name = "xinfangshuo" tu = ("zhao","qian","sun") lt = ["zhao","qian","sun"] dic = {"a":1,"b":2,"c":3,"d":4} se = {"zhao","qian","sun","li","zhou"} print (len(se))
5.raw_input()/input()输入
#python2.x 中 raw_input("请输入账号:") raw_input("请输入密码:") print "登录成功" name = raw_input("请告诉我你的名字:") print "好的," + name
#python3.x 中 #简单整数加法计算器 num1 = input("请输入第一个数字:") num2 = input("请输入第二个数字:") print (int(num1) + int(num2))
6.type()用于查看字符类型
num = input("请输入第一个数字:") print (type(num))
7.abs()返回数字的绝对值
num1 = input("请输入第一个数字:") num2 = input("请输入第二个数字:") print (abs(int(num1) + int(num2)))
8. 最大值、最小值、求和
- max()返回最大值
- min()返回最小值
- sum()返回和
list1 = [1,3,4,5,34,79,12,4] list2 = [1,3,4,5,79,12,4] print (max(list1)) print (min(list1)) print (sum(list1)-sum(list2))
9.open()打开文件
file4 = open('d:\test1.txt','r') for i in file4.readlines(): print (i) file4.close()
10.range()用于创建一个整数列表,一般用在 for 循环中
print (range(5)) print (range(1,5)) print (range(0,5,2))
list1 = [] for i in range(101): if i % 2 ==0: list1.append(i) print (sum(list1)) sum1 = 0 for i in range(0,101,2): sum1 += i print (sum1)
11.enumerate()函数用于将一个可遍历的数据对象(如列表、元组或字符串)组合为一个索引序列,同时列出数据和数据下标,一般用在 for 循环当中。
- enumerate(sequence, [start=0])
- sequence -- 一个序列
- start -- 下标起始位置。
Fruits = ["Apple","Banana","Orange"] for i in enumerate(Fruits): print(i) ---> (0, 'Apple') ---> (1, 'Banana') ---> (2, 'Orange')
Fruits = ["Apple","Banana","Orange"] for i in enumerate(Fruits,1): print(i) ---> (1, 'Apple') ---> (2, 'Banana') ---> (3, 'Orange')
Fruits = ["Apple","Banana","Orange"] for x,y in enumerate(Fruits,1): print(x,":",y) ---> 1 : Apple ---> 2 : Banana ---> 3 : Orange