GPA Calc Python

Question

我不断得到一个错误的GPA计算器，它应该计算你的GPA基于4个等级。此外，每当输入一个不是A、B、C、D、F的字母时，程序都需要终止，我不知道该怎么做。

def GetName():
    name = raw_input ("Enter the student's name  ")
    grade1 = raw_input ("Enter a grade:  ")
    grade2 = raw_input ("Enter a grade:  ")
    grade3 = raw_input ("Enter a grade:  ")
    grade4 = raw_input ("Enter a grade:  ")
    return name, grade1, grade2, grade3, grade4

def GetGrades(grade1, grade2, grade3, grade4):
        if [grade1, grade2, grade3, grade4] == 'A' or [grade1, grade2, grade3, grade4] == 'a':
                [g1, g2, g3, g4] =4
        elif [grade1, grade2, grade3, grade4] == 'B' or [grade1, grade2, grade3, grade4] ==  'b':
                [g1, g2, g3, g4] =3
        elif [grade1, grade2, grade3, grade4] == 'C' or [grade1, grade2, grade3, grade4] == 'd':
                [g1, g2, g3, g4] =2
        elif [grade1, grade2, grade3, grade4] == 'D' or [grade1, grade2, grade3, grade4] == 'd':
                [g1, g2, g3, g4] =1
        elif [grade1, grade2, grade3, grade4] == 'F' or [grade1, grade2, grade3, grade4] == 'f':
                [g1, g2, g3, g4] =0
        else:
                return 'invalid grade'
        return g1, g2, g3, g4

def CalcGPA(g1,g2,g3,g4):
    GPA = (g1,g2,g3,g4)/4
    return GPA


def main(name, GPA):
    print "The GPA for", name,"is",GPA
    return 0

GetName()=name,grade1,grade2,grade3,grade4
GetGrades(grade1,grade2,grade3,grade4)=g1,g2,g3,g4
CalcGPA(g1,g2,g3,g4)=GPA
main(name,GPA)=0

Answer 1

Python中的赋值将等号右侧的值赋给左侧的引用，因此要解包的元组必须位于左侧。

def GetName():
    name = raw_input("Enter the student's name  ")
    grade1 = raw_input("Enter a grade:  ")
    grade2 = raw_input("Enter a grade:  ")
    grade3 = raw_input("Enter a grade:  ")
    grade4 = raw_input("Enter a grade:  ")
    return name, grade1, grade2, grade3, grade4

grademap = { 'A': 4, 'B': 3, 'C': 2, 'D': 1 }

def grade2int(x):
    try:
        return grademap[x.upper()]
    except KeyError:
        raise Exception('invalid grade: ' + x)

def GetGrades(grades):
    return map(grade2int, grades)

def CalcGPA(grades):
    return sum(grades)/len(grades)

def main(name, GPA):
    print "The GPA for", name, "is", GPA
    return 0

if __name__ == '__main__':
    name, grade1, grade2, grade3, grade4 = GetName()
    grades = GetGrades([grade1, grade2, grade3, grade4])
    GPA = CalcGPA(grades)
    main(name, GPA)

Answer 2

看起来有一些错误，这里有一些提示。

首先，在你的列表中，grade1，grade2，grade3，grade4永远不会等于'A‘，它只会等于一个列表，所以你必须重新考虑如何测试成绩。

其次，你需要成绩值的总和，并想除以一个浮点数，否则python会去掉小数(除非g1-4是用小数输入的)。

def CalcGPA(g1,g2,g3,g4):
    GPA = sum(g1,g2,g3,g4)/4.0
    return GPA

第三，错误来自如何调用函数的语法应该是：

name,grade1,grade2,grade3,grade4= GetName()
g1,g2,g3,g4=GetGrades(grade1,grade2,grade3,grade4)
GPA = CalcGPA(g1,g2,g3,g4)
0=main(name,GPA)

至于让程序在输入无效成绩时结束，您可以考虑放入一个while循环，该循环在grad无效时结束。