python基础5-函数、类和文件操作

def myabs(x):
    if x>0:
        return x
    else:
        return -x

f = lambda x,y,z:x+y+z
print(f(1,2,3)) #6
L = [(lambda x:x**2),(lambda x:x**3)]
print(L[0](3),L[1](3)) #(9, 27)

class Car:
    def infor(self):
        print("This is a car")
car = Car()
car.infor() #This is a car

s = "hello world"
with open(‘sample.txt‘,‘a+‘) as f:
    f.write(s)

f = open(‘sample.txt‘,‘r‘)
print(fp.read(5)) #读取前5字节
f = open(‘sample.txt‘,‘r‘)
while True:
    line = f.readline()
    if line==‘‘:
        break
    print line,
    f.close()