Question

你好，我是正则表达式的新手

^0* - 
g
^ asserts position at start of the string
0* matches the character 0 literally (case sensitive)
* Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Global pattern flags
g modifier: global. All matches (don't return after first match)

for String“3454tdfgffg”它应该返回false，因为没有零

下面的

是我的例子

public class RegExTest {

    public static void main(String args[]){
          String pattern ="^0*";

          String instance = "3454tdfgffg";

          // Create a Pattern object
          Pattern r = Pattern.compile(pattern);

          // Now create matcher object.
          Matcher m = r.matcher(instance);
          if (m.find()) {
              System.out.println("Available");
          }else
          {
              System.out.println("Not available");
          }

    }
}

但它始终返回true，我在实例变量

中编写的内容

你能解决我，我错了吗

Answer 1

它将永远返回true。

party_tomorrow = CalendarEvent( starts = datetime.datetime.today() + datetime.timedelta(days = 1), ends = datetime.datetime.today() + datetime.timedelta(days = 1, hours = 5), repeat = None, end_repeat = None, travel_time = datetime.timedelta(hours = 1), alert = None, notes = "This is gonna be a load of fun.", invitees = None )匹配零和无限次之间重复的字符Traceback (most recent call last): File "/Users/George/Library/FlashlightPlugins/calendarquery.bundle/plugin.py", line 62, in test_CalendarEvent invitees = None File "/Users/George/Library/FlashlightPlugins/calendarquery.bundle/plugin.py", line 12, in __init__ for key, value in keyword_arguments: ValueError: too many values to unpack (expected 2)。在您的字符串中，此字符缺失，因此这意味着字符0* 重复零次，匹配将按预期返回0。

如果您需要匹配至少一个零，请使用0

^ 0 *正则表达式不工作java

1 个答案: