将一个功能放到另一个功能上遇到麻烦

Question

what i'm trying to do is to read each line of the file then put it into other function called handleLine which then creates output, numericgrade calculates the overall percentage and then lettergrade assigns a grade.

for example in file i have "name, last name", classid, exam, final and i want it to output full name, score , grade

def main():
    fin=open("scores.csv", "r")
    fout=open("grades.csv", "w")
    fout.write('"Name", "Score", "Grade"\n')
    line=fin.readlines()[1:]
    for line in line:
        line=line.split(",")
        handleLine(line)
        fout.write('"' + lname + "," + fname + '" ,' + score +", " + grade+ ' ", ')

def numericGrade(midterm, final):
    score=0.4*float(midterm) + (0.6 * float(final))
def letterGrade(score):
    grade = None
    if score >= 90:
        grade = "A"
    elif score >= 80:
        grade = "B"
    elif score >=70:
        grade ="C"
    elif score >= 60:
        grade = "D"
    else:
        grade = "F"
def handleLine(line):
    fout=open("grades.csv", "w")
    fname= line[1][1 : -1]
    lname= line[0][1 : ]
    midterm= line[2]
    final = line[3]
    numericGrade(midterm, final)
    score = numericGrade(midterm,final)
    grade = letterGrade(score)
    return lname, fname, score, grade
if __name__=="__main__":

main()

I'm having trouble putting one function to another, now it says that lname is not defined in line 14. Im really lost now.

EDIT: I have fixed the

lname, fname, score, grade= handleLine(line)

but i have an error now in line 14

TypeError: cannot concatenate 'str' and 'NoneType' objects

Answer 1

仅返回值 ，而不返回名称。

lname, fname, score, grade = handleLine(line)

Answer 2

When you return a value from a function, the name of the value is not what it was inside the function, but what you call it when the function returns.

def myfunction():
   num = 5 
   return num  #returns 5


variableThatIsNotCalledNum = myfunction()
# my long named variable now holds the value 5

#error: no such variable around here
print num 

# prints the 5
print variableThatIsNotCalledNum 

One other thing, numericGrade() and letterGrade() need to return score and grade respectively.