減去代碼

Question

我需要從4號線減去5號線，如果負輸入0兩行，這樣下去上來

def main(): 
    print("IRS Form 1040EZ Tax Computation Program (2015)") 
    print() 
    sal = eval(input("Line 1: Enter wages, salaries, and tips: ")) 
    tint = eval(input("Line 2: Enter taxable interest: ")) 
    print() 
    agros = print("Line 4: Adjusted Gross Income: ",sal + tint) 
    print() 
    exempt = eval(input("Line 5: Exemption Amount $ ")) 
    print("Line 6: Taxable Income: $",agros - exempt) 

main() 

IRS Form 1040EZ Tax Computation Program (2015) 

Line 1: Enter wages, salaries, and tips: 27500.00 
Line 2: Enter taxable interest: 250.00 

Line 4: Adjusted Gross Income: 27750.0 

Line 5: Exemption Amount $ 10150 

Traceback (most recent call last): 
    line 22, in main 
    print("Line 6: Taxable Income: $",agros - exempt) 
TypeError: unsupported operand type(s) for -: 'NoneType' and 'int' 

Answer 1

在行

agros = print("Line 4: Adjusted Gross Income: ",sal + tint) 

要分配agros調用print的結果：

>>> a = print("") 
>>> print(a) 
None 

您需要單獨做任務和打印：

agros = sal + tint 
print("Line 4: Adjusted Gross Income: ", agros) 

Answer 2

不是一個真正的蟒蛇的傢伙，但我會嘗試：

agros = sal + tint 
print("Line 4: Adjusted Gross Income: ", agros)