python名称错误：名称'；还清债务'；没有定义

当我以这种方式尝试代码时，效果很好：

#this block of code will get the necessary inputs from the user

or_balance=balance=float(input('Enter the outstanding balance on your credit card: '))
int_rate=float(input('Enter the annual credit card interest rate as a decimal: '))
mon_int_rate=int_rate/12

#this block of code will deal with the inputs to get the outputs

mon_pay_low_bound=balance/12
mon_pay_up_bound=(balance*(1+mon_int_rate)*12)/12

def total_balance(mon_pay):
    balance=or_balance
    global num
    num=0
    while num<12:
        num+=1
        balance=balance*(1+mon_int_rate)-mon_pay

    return balance

#this block of code will get the result desired by using the bisection method

a=mon_pay_low_bound
b=mon_pay_up_bound
tol=.0000000000005
n=1
while n<999:
    c=(a+b)/2
    if total_balance(c)==0 or (b-a)/2<tol:

        break
    else:
        n+=1
        if total_balance(c)<0:
            b=c
        else:
            a=c

#this block of code will give the final results
print('RESULT')
print('Monthly payment to pay off debt in 1 year:',round(c,2))
print('Number of months needed:',num)
print('Balance',round(total_balance(c),2))

#此代码块将从用户处获得必要的输入
或者_balance=balance=float（输入（'在您的信用卡上输入未付余额：'））
int_rate=float（输入（'以十进制形式输入信用卡年利率：'））
mon_int_rate=int_rate/12
#这段代码将处理输入以获得输出
mon\u pay\u low\u bound=余额/12
周一支付上限=（余额*（1+周一国际汇率）*12）/12
def总余额（周一支付）：
平衡
全局数
num=0
而num如果这个
总平衡（c）==0或（b-a）/2如其他人所说，这是因为
总平衡（c）==0或（b-a）/2定义了while之外的变量loop@matcheek问题不在于
while
循环，而是他在
if/else
中设置了变量。如果
If
的计算结果从未为true，则从未设置变量，这可能是
名称错误的原因
while n<999:
    c=(a+b)/2
    if total_balance(c)==0 or (b-a)/2<tol:
        pay_off=c
        break
    else:
        n+=1
        if total_balance(c)<0:
            b=c
        else:
            a=c

#this block of code will give the final results
print('RESULT')
print('Monthly payment to pay off debt in 1 year:',round(pay_off,2))
print('Number of months needed:',num)
print('Balance',round(total_balance(pay_off),2))

pay_off=0
while n<999:
    c=(a+b)/2
    if total_balance(c)==0 or (b-a)/2<tol:
        pay_off=c
        break
    else:
        n+=1
        if total_balance(c)<0:
            b=c
        else:
            a=c
if pay_off == 0:
    print "I couldn't determine the payoff amount in %d iterations" % n