3v4l.org

run code in 300+ PHP versions simultaneously
<?php $string = "[vc_tab [vc_tab [vc_tab [vc_tab [vc_tab [vc_tab"; $active = 3; $needle = "[vc_tab"; $replace = '[vc_tab active="true"'; if( substr_count( $string, $needle) < $active) { throw new Exception("There aren't enough needles in the string to do this replacement"); } $count = 0; $index = 0; while( $count++ < $active) { $index = strpos( $string, $needle, $index) + strlen( $needle); } echo "Index: ", $index, " ", substr( $string, index);

preferences:
46.07 ms | 402 KiB | 5 Q