PROGRAM 3:Write a PHP Program the String MAnipulation

<?php
echo"STRING REPLACE";
echo "<br>";echo "<br>";
echo str_replace("ARTS","SCIENCE","GOBI  ARTS");
echo "<br>";echo "<br>";
echo"STRING WORD COUNT";
echo "<br>";echo "<br>";
echo str_word_count("GOBI ARTS");
echo "<br>";echo "<br>";
echo"STRING CASE COMPARE";
echo "<br>";echo "<br>";
echo strcasecmp("Hello","HELLO");
echo "<br>";echo "<br>";
echo"STRING COMPARE";
echo "<br>";echo "<br>";
echo strcmp("Hello world!","GOBI ARTS");
echo "<br>";echo "<br>";
echo strcmp("Hello world!","Hello world!");
echo "<br>";echo "<br>";
echo("STRING LENGTH");
echo "<br>";echo "<br>";
echo strlen("Hello world!");
?>