1 def main():
 2     fileName=input("What file are the numbers in?")
 3     infile=open(fileName,'r')
 4     sum=0
 5     count=0
 6     for line in infile:
 7         sum=sum+eval(line)
 8         count=count+1
 9     print("\nThe average of the numbers is",sum/count)
10 main()

 方法二：

采用readline（）方法的end-of-file循环模式

1 line=infile.readline()
2 while line!=""
3     #处理每一行
4     line=infile.readline()

 ==========================

循环嵌套 

*决策和循环相互嵌套可以实现复杂算法

*如果数字以逗号分隔出现在文件的同一行上

1 for xStr in line.split(",")
2     sum=sum+eval(xStr)
3     count=count+1