Python报错TypeError:无法解包NoneType对象，明明已返回值

核心问题 #

你的search函数在递归分支（elif savings < required_down和else块）中调用了search()，但没有将递归调用的结果返回。这会导致当程序进入这些分支时，函数执行完递归后没有返回任何值，默认返回None，而调用方userInput()试图将None解包成两个变量，因此触发TypeError。

修复代码 #

修改search函数的递归分支，添加return关键字传递递归结果：

def search(start, end, step, salary, savings, r, required_down, semi, months):
    test_value = (start+end)/2
    original_salary = salary
    while savings <= required_down and months <= 36:
        if months != 0 and months%6 == 0:
            salary *= 1+semi
        savings += (savings*r/12) + (salary/12)*(test_value/10000)
        months+=1
    if required_down - 500 < savings < required_down + 500:
        return test_value, step
    elif savings < required_down:
        savings = 0
        months = 0
        # 添加return传递递归结果
        return search(test_value, end, step + 1, original_salary, savings, r, required_down, semi, months)
    else:
        savings = 0
        months = 0
        # 添加return传递递归结果
        return search(start, test_value, step + 1, original_salary, savings, r, required_down, semi, months)
    if step >= 25:
        rate = 'n/a'
        steps = 'n/a'
        return rate,steps

额外优化说明 #

• 你原本的step >=25判断逻辑永远不会被执行，因为前面的if/elif/else已经覆盖了所有情况，属于不可达代码。建议将递归终止条件移到函数开头，避免逻辑冗余：

def search(start, end, step, salary, savings, r, required_down, semi, months):
    # 优先检查递归终止条件
    if step >= 25:
        return 'n/a', 'n/a'
    
    test_value = (start+end)/2
    original_salary = salary
    current_savings = savings
    current_months = months
    
    while current_savings <= required_down and current_months <= 36:
        if current_months != 0 and current_months % 6 == 0:
            salary *= 1 + semi
        current_savings += (current_savings * r / 12) + (salary / 12) * (test_value / 10000)
        current_months += 1
    
    if required_down - 500 < current_savings < required_down + 500:
        return test_value / 10000, step  # 直接返回实际利率，无需调用方额外转换
    elif current_savings < required_down:
        return search(test_value, end, step + 1, original_salary, 0, r, required_down, semi, 0)
    else:
        return search(start, test_value, step + 1, original_salary, 0, r, required_down, semi, 0)

内容的提问来源于stack exchange，提问作者ted