python-3.x - 处理数学时如何“跳过”空白输入？（Python）

Question

我正在研究 GPA 计算器以熟悉 python/编程。当每个班级都有输入时，我让它工作。但是，我不确定如果没有为课程学分/等级输入任何内容，或者使其充当空白数字，我将如何跳过该变量。

我尝试向字典中添加一个空白字符串并将其设置为无，但仍然出现错误。

grades = {
    'A+' : 4.00,
    'A' : 4.00,
    'A-' : 3.67,
    'B+' : 3.33,
    'B' : 3.00,
    'B-' : 2.67,
    'C+' : 2.33,
    'C' : 2.0,
    'C-' : 1.67,
    'D+' : 1.33,
    'D' : 1.0,
    'F' : 0.0,
    }

grd_num = []
cred = []

grd_num.append(grades[input('Enter the letter grade for your first class\n')])
cred.append(float(input('Enter the amount of credits that your first class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your second class\n')])
cred.append(float(input('Enter the amount of credits that your second class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your third class\n')])
cred.append(float(input('Enter the amount of credits that your third class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your fourth class\n')])
cred.append(float(input('Enter the amount of credits that your fourth class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your fith class\n')])
cred.append(float(input('Enter the amount of credits that your fith class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your sixth class\n')])
cred.append(float(input('Enter the amount of credits that your sixth class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your seventh class\n')])
cred.append(float(input('Enter the amount of credits that your seventh class is worth\n')))

grd_num.append(grades[input('Enter the letter grade for your eighth class\n')])
cred.append(float(input('Enter the amount of credits that your eighth class is worth\n')))


totGPA = ((grd_num[0] * cred[0]) + (grd_num[1] * cred[1]) + (grd_num[2] * cred[2]) + (grd_num[3] * cred[3]) + (grd_num[4] * cred[4]) + (grd_num[5] * cred[5]) + (grd_num[6] * cred[6]) + (grd_num[7] * cred[7]))/sum(cred)

print(totGPA)

我希望用户能够输入任意数量的课程，从 1 到 8。目前，用户只能输入 8 个课程而不会出错。

标签： python-3.xmathinput

Answer 1

这是我能想到的解决方法。您可以检查用户输入是否为空并相应地中断输入序列。

grd = input('Enter the letter grade for your first class\n')
if grd != "":
    grd_num.append(grades[grd])
    cred.append(float(input('Enter the amount of credits that your first class is worth\n')))
else:
    grd_num.append(0.0)
    cred.append(0.0)

if grd != "":
    grd = input('Enter the letter grade for your second class\n')
    if grd != "":
        grd_num.append(grades[grd])
        cred.append(float(input('Enter the amount of credits that your second class is worth\n')))
    else:
        grd_num.append(0.0)
        cred.append(0.0)
else:
    grd_num.append(0.0)
    cred.append(0.0)


if grd != "":
    grd = input('Enter the letter grade for your third class\n')
    if grd != "":
        grd_num.append(grades[grd])
        cred.append(float(input('Enter the amount of credits that your third class is worth\n')))
    else:
        grd_num.append(0.0)
        cred.append(0.0)
else:
    grd_num.append(0.0)
    cred.append(0.0)

# REPEAT REPEAT REPEAT ...

if grd != "":
    grd = input('Enter the letter grade for your eighth  class\n')
    if grd != "":
        grd_num.append(grades[grd])
        cred.append(float(input('Enter the amount of credits that your eighth class is worth\n')))
    else:
        grd_num.append(0.0)
        cred.append(0.0)
else:
    grd_num.append(0.0)
    cred.append(0.0)

通过检查用户输入是否为空，您可以有效地停止提示输入并用零填充剩余的数据。