如何在PHP中使用正则表达式获取日期字符串位置

Question

在以下示例中，如何使用php正则表达式获取日期字符串的位置？

例如，我想知道“ 2011年12月31日”或“ 2011年12月31日”的职位。 日期格式为“年月日”或“年月日”

<TR>
<TD VALIGN="top" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>December 31, 2011</B></FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>(Date of Event Which Requires Filing of this Statement) </B></FONT></P>
<P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>Check the appropriate box to designate the rule pursuant to which this Schedule is filed: </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:8%"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B></B><FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><B></B><B> Rule 13d-1 (b) </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:8%"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B></B><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT><B></B><B> Rule 13d-1 (c) </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:8%"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B></B><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT><B></B><B> Rule 13d-1 (d) </B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>

Answer 1

<?php
$str = '<TR>
<TD VALIGN="top" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="2"><B>December 31, 2011</B></FONT></TD></TR>
</TABLE> <P STYLE="margin-top:0px;margin-bottom:0px" ALIGN="center"><FONT STYLE="font-family:Times New Roman" SIZE="1"><B>(Date of Event Which Requires Filing of this Statement) </B></FONT></P>
<P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P><center> <P STYLE="line-height:6px;margin-top:0px;margin-bottom:2px;border-bottom:1pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12px;margin-bottom:0px"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B>Check the appropriate box to designate the rule pursuant to which this Schedule is filed: </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:8%"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B></B><FONT STYLE="FONT-FAMILY:WINGDINGS">&#120;</FONT><B></B><B> Rule 13d-1 (b) </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:8%"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B></B><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT><B></B><B> Rule 13d-1 (c) </B></FONT></P> <P STYLE="margin-top:12px;margin-bottom:0px; margin-left:8%"><FONT
STYLE="font-family:Times New Roman" SIZE="2"><B></B><FONT STYLE="FONT-FAMILY:WINGDINGS">&#168;</FONT><B></B><B> Rule 13d-1 (d) </B></FONT></P> <P STYLE="font-size:12px;margin-top:0px;margin-bottom:0px">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR>';

$matches = array();
preg_match('/(\w+ \d{1,2},? \d{4})/', $str, $matches); // search for date

$position = strpos($str, $matches[0]);  // Find position
?>

Answer 2

您不必一定要使用正则表达式。 php内置函数strpos（http://us2.php.net/manual/zh/function.strpos.php）将为您提供传递给它的所有内容的第一次出现的字符串索引。

因此，您可以在字符串中搜索月份的名称，例如：

<?php
$mystring = 'abc';
$findme   = 'a';
$pos = strpos($mystring, $findme);

// Note our use of ===.  Simply == would not work as expected
// because the position of 'a' was the 0th (first) character.
if ($pos === false) {
    echo "The string '$findme' was not found in the string '$mystring'";
} else {
    echo "The string '$findme' was found in the string '$mystring'";
    echo " and exists at position $pos";
}
?>