python入门奶牛问题

Python 3.9.13 (tags/v3.9.13:6de2ca5, May 17 2022, 16:36:42) [MSC v.1929 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license()" for more information. >>> print("Python"+str(3.7)) Python3.7 >>> print("Python"+3.7) Traceback (most recent call last): File "<pyshell#1>", line 1, in <module> print("Python"+3.7) TypeError: can only concatenate str (not "float") to str >>> a=2 >>> b=3 >>> c=a**b >>> print(c) 8 >>> a 2 >>> b 3 >>> d Traceback (most recent call last): File "<pyshell#8>", line 1, in <module> d NameError: name 'd' is not defined >>> print('hello,world') hello,world >>> print('hello','world') hello world >>> print('hello'+'world') helloworld >>> print('a'*3) aaa >>> a=3 >>> (float)a SyntaxError: invalid syntax >>> print(5/3) 1.6666666666666667 >>> print(5//3) 1 >>> print(float(8)) 8.0 >>> type(4/2) <class 'float'> >>> 4/2 2.0 >>> n=input('请输入奶牛的头数') 请输入奶牛的头数10 >>> day=7 >>> product=20 >>> print(n+'头奶牛'+day+'天可以产'+day*product*n+'千克的牛奶') Traceback (most recent call last): File "<pyshell#23>", line 1, in <module> print(n+'头奶牛'+day+'天可以产'+day*product*n+'千克的牛奶') TypeError: can only concatenate str (not "int") to str >>> print(str(n)+'头奶牛'+str(day)+'天可以产'+str(day*product*n)+'千克的牛奶') 10头奶牛7天可以产1010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010千克的牛奶 >>> d=day*product*n >>> print(d) 1010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010 >>> d=day*product >>> print(d) 140 >>> d=d*n >>> print(d) 1010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010 >>> print(n) 10 >>> type(n) <class 'str'> >>> d=day*product*int(n) >>> print(d) 1400 >>> print(str(n)+'头奶牛'+str(day)+'天可以产'+str(d)+'千克的牛奶') 10头奶牛7天可以产1400千克的牛奶 >>>