<?php
//正则表达式中的逆向引用($0-99或\\0-99)和子模式以(/()/)开始
$string = "{April 15, 2003}";
//'w'匹配字母，数字和下划线，'d'匹配0-99数字，'+'元字符规定其前导字符必须在目标对象中连续出现一次或多次
$pattern = "/{(\w+) (\d+), (\d+)}/i"; //在字符串中要搜索的匹配项
$replacement1 = "\${1}1,\$3";
$replacement2 = "\$0";
$replacement3 = "\$1";
$replacement4 = "\$2";
$replacement5 = "\$3";
echo "<BR>";
//字符串被替换为与第 n 个被捕获的括号内的子模式所匹配的文本
print preg_replace($pattern, $replacement1, $string);
echo "<BR>";
print preg_replace($pattern, $replacement2, $string);
echo "<BR>";
print preg_replace($pattern, $replacement3, $string);
echo "<BR>";
print preg_replace($pattern, $replacement4, $string);
echo "<BR>";
print preg_replace($pattern, $replacement5, $string);
echo "<BR>"
//一般表现形式
print preg_replace("/\w+/i","j",$string);
?>
结果:
April1,2003
{April 15, 2003}
April
15
2003
{j j, j}