# initialization phase
total = 0 # sum of grades
gradeCounter = 0 # number of grades entered
# processing phase
grade = raw_input( "Enter grade, -1 to end: " ) # get one grade
grade = int( grade ) # convert string to an integer
while grade != -1:
total = total + grade
%获取分数的总和
gradeCounter = gradeCounter + 1
%分数的个数
grade = raw_input( "Enter grade, -1 to end: " )
%获取分数的输入
grade = int( grade )
%将string型转化为int型
# termination phase
if gradeCounter != 0:
average = float( total ) / gradeCounter
%获取平均值
print "Class average is", average
%打印平均值
else:
print "No grades were entered"
%否则提示错误