python--文件操作/异常捕获/继承

一、文件操作

spath="D:/test/baa.txt" #设置spath值为路径
f=open(spath,"w") #以写的权限打开文件夹，此时baa.txt不存在。
f.write("First line 1.\n")#写入First line 1 回车
f.writelines("First line 2.")+#向此前已打开的文本文件尾追加一行数据.

f.close()#关闭文件操作

f=open(spath,"r") # 以读权限打开文件

for line in f:
    print line

f.close()

 

 

运行结果：

First line 1.

First line 2.

 

二、异常捕获

s=raw_input("Input your age:")
if s =="":
    raise Exception("Input must no be empty.")

try:
    i=int(s)
except ValueError:
    print "Could not convert data to an integer."
except:
    print "Unknown exception!"
else: # It is useful for code that must be executed if the try clause does not raise an exception
    print "You are %d" % i," years old"
finally: # Clean up action
    print "Goodbye!"

 

运行结果：

Input your age:ad
Could not convert data to an integer.
Goodbye!

 

三、继承

 

class Base:
    def __init__(self):
        self.data = []
    def add(self, x):
        self.data.append(x)
    def addtwice(self, x):
        self.add(x)
        self.add(x)

# Child extends Base
class Child(Base):
    def plus(self,a,b):
        return a+b

oChild =Child()
oChild.add("str1")
print oChild.data
print oChild.plus(2,3)

 

 

运行结果：

['str1']
5