我想在Python3中打印由字符串分隔的整数变量字符串

Question

我试图打印3个整数变量之间的一些字符串分隔。但这给了我一个错误

TypeError: unsupported operand type(s) for +: 'int' and 'str'.

我的尝试：

def unpack_values(grades):
     first, *middle, last = grades
     avg = sum(middle)/len(middle)
     print(str(first)+"-------"+str(avg)+" ---- "+str(last))

unpack_values(['10', '20', '30', '40', '50'])

Answer 1

尝试计算sum(middle)时出错，因为middle是字符串列表。你需要先把它转换成整数。你知道吗

In [1]: def unpack_values(grades):
   ...:     first, *middle, last = [int(g) for g in grades]
   ...:     avg = sum(middle) / len(middle)
   ...:     print('{}     {}     {}'.format(first, avg, last))
   ...:     

In [2]: unpack_values(['10', '20', '30', '40', '50'])
10     30.0     50