3v4l.org

run code in 300+ PHP versions simultaneously
<?php function replaceStrAt($str, $substr, $from, $to = null){ is_null($to) and $to = $from; return mb_substr($str, 0, $from) . $substr . mb_substr($str, $to + 1); } function insertSubstrInto($str, $substr, $index){ return mb_substr($str, 0, $index) . $substr . mb_substr($str, $index); } $s = 'И просто текст'; echo replaceStrAt($s, "\t", 4), "\n"; echo insertSubstrInto($s, "\t", 4), "\n";
Output for 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.34, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
И пр сто текст И пр осто текст

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220.05 ms | 403 KiB | 296 Q