print " What is your name?"
myName= raw_input()
print ('the length of your name is '+str(len(myName)) )

输入line3时曾犯的错误：

print ('the length of your name is ',len(myName))
输出结果为：
What is your name?
han meimei
('the length of your name is ', 10)

line3显示为一元组

File "len().py", line 3, in <module>
print ('the length of your name is '+ len(myName))
TypeError: cannot concatenate 'str' and 'int' objects

将逗号改为加号后，字符串与数值属于不同类型数据，无法相加