Python入门简短实例摘录
Python入门简短实例摘录
这十个小题目是任何一门语言最基本的入门，为方便后续浏览而摘录下来。大部分实例摘自网站：http://askpython.com，英文原版短文。有想读英文原版的朋友可以浏览此站点。
1. Hello world：
#!/usr/bin/env python3
print('hello world')
2. 变量【可以不用声明，自动识别变量类型】
#!/usr/bin/python x = 3 # a whole number f = 3.1415926 # a floating point number name = "Python" # a string print(x) print(f) print(name) combination = name + " " + name print(combination) sum = f + f print(sum)
3. 键盘输入【Python2x可以接收字符串或者数字，但是Python3x只接收数字时需要强制转换】
#!/usr/bin/env python3
name = input('What is your name? ')
print('Hello ' + name)
num = input('Give me a number? ')
print('You said: ' + str(num))
4. 条件语句
!/usr/bin/env python3
age = int(input("Age of your cat? "))
if age < 5:
print("Your cat is young.")
elif age > 10:
print("Your cat is old.")
else:
print("Your cat is adult.")
5. for循环
#!/usr/bin/env python3
city = ['Tokyo','New York','Toronto','Hong Kong']
for x in city:
print(x)
#!/usr/bin/env python3
num = [1,2,3,4,5,6,7,8,9]
for x in num:
y = x * x
print(y)
5. while循环
#!/usr/bin/python
x = 3
while x < 10:
print(x)
x = x + 1
#!/usr/bin/python
while True:
if condition:
break
6. 函数
#!/usr/bin/env python3
def f(x,y):
print(x*y)
f(3,4)
#!/usr/bin/env python3
def sum(list):
sum = 0
for l in list:
sum = sum + l
return sum
mylist = [1,2,3,4,5]
print(sum(mylist))
7. 元组 【下标起始0，-1指示最后一个元素】
list = [1,3,4,6,4,7,8,2,3] print(sum(list)) print(min(list)) print(max(list)) print(list[0]) print(list[-1])
8. 字典【无序存储结构】
注：使用Python3x运行如下脚本，着重注意print必须带有括号，如print(words["BMP"])，这是与Python2x中print的区别。
#!/usr/bin/python
words = {}
words["BMP"] = "Bitmap"
words["BTW"] = "By The Way"
words["BRB"] = "Be Right Back"
print words["BMP"]
print words["BRB"]
9. 读取文件：
按行读取：
#!/usr/bin/env python
filename = "file.py"
with open(filename) as f:
content = f.readlines()
print(content)读取文件内容到一个字符串：
#!/usr/bin/env python filename = "file.py" infile = open(filename, 'r') data = infile.read() infile.close() print(data)
10. 写文件：
创建一个文件：
#!/usr/bin/env python
# create and open file
f = open("test.txt","w")
# write data to file
f.write("Hello World, \n")
f.write("This data will be written to the file.")
# close file
f.close()添加内容到文件末尾：
#!/usr/bin/env python
# create and open file
f = open("test.txt","a")
# write data to file
f.write("Don't delete existing data \n")
f.write("Add this to the existing file.")
# close file
f.close(