Question

我正在处理带有异常处理的输入验证，我的代码可以工作，但是它会打印错误消息两次，我无法弄清楚如何使验证循环只打印其中一个错误消息而不是两者。

这是我的代码：

def main():
    low = 0
    high = 10
    get_num_in_range(low,high)

def get_num_in_range (low,high):
    prompt = 'Enter a number between: ' + str(low) + ' and ' + str(high) + ': '
    answer = low-1 #just get me in to loop
    while answer < low or answer > high:
        try:
            answer = int(input(prompt))
        except ValueError:
            print('Invalid data type!')
        if answer < low or answer > high:
            print('Invalid!')
    return answer

main()

输出如下：

输入介于0和10之间的数字：a

数据类型无效！

无效！

输入介于0和10之间的数字：

如何让循环只打印相关的错误消息？

编辑：解决了哈！我是一个白痴我在异常处理程序之外进行了'if'验证。固定代码：

while answer < low or answer > high:
    try:
        answer = int(input(prompt))
            if answer < low or answer > high:
                print('Invalid!')
    except ValueError:
        print('Invalid data type!')
return answer

Answer 1

另一种选择可能是查看try-except-else子句（https://docs.python.org/2/tutorial/errors.html）。

    CREATE TABLE "TASK_LIST"
    (    
       "TASK_ID" INT not null primary key GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),   
       "TASK_NAME" VARCHAR(50),     
       "TASK_DESCRIPTION" VARCHAR(50),
       "TASK_PRIORITY" VARCHAR(100),
       "TASK_STATUS" VARCHAR(20),
       "TASK_START_TIME" TIMESTAMP,  
       "TASK_END_TIME" TIMESTAMP,
       "TASK_ARCHIVED" BOOLEAN 
    );

    //...NOTE: the task_id column value is auto-generated...
    insert into task_list (task_name, task_description, task_priority, task_status, task_start_time, task_end_time, task_archived) values('Gathering Requirement',    'Requirement Gathering',    'MEDIUM',   'ACTIVE', CURRENT TIMESTAMP, {fn TIMESTAMPADD(SQL_TSI_HOUR, 1, CURRENT_TIMESTAMP)}, false);
    insert into task_list (task_name, task_description, task_priority, task_status, task_start_time, task_end_time, task_archived) values('Application Designing',    'Application Designing',    'MEDIUM',   'ACTIVE', CURRENT TIMESTAMP, {fn TIMESTAMPADD(SQL_TSI_HOUR, 2, CURRENT_TIMESTAMP)}, false);
    insert into task_list (task_name, task_description, task_priority, task_status, task_start_time, task_end_time, task_archived) values('Implementation',           'Implementation',           'MEDIUM',   'ACTIVE', CURRENT TIMESTAMP, {fn TIMESTAMPADD(SQL_TSI_HOUR, 3, CURRENT_TIMESTAMP)}, false);
    insert into task_list (task_name, task_description, task_priority, task_status, task_start_time, task_end_time, task_archived) values('Unit Testing',             'Unit Testing',             'LOW',      'ACTIVE', CURRENT TIMESTAMP, {fn TIMESTAMPADD(SQL_TSI_HOUR, 4, CURRENT_TIMESTAMP)}, false);
    insert into task_list (task_name, task_description, task_priority, task_status, task_start_time, task_end_time, task_archived) values('Maintenance',              'Maintenance',              'LOW',      'ACTIVE', CURRENT TIMESTAMP, {fn TIMESTAMPADD(SQL_TSI_HOUR, 5, CURRENT_TIMESTAMP)}, false);

当没有捕获异常时调用else子句

输入验证冗余

1 个答案: