<?php
/*
String Functions
- substr_replace(String[Required], Replace With Or Insert[Required], Start[Required], Length[$])
--- $ Positive Number => Length Of String To Be Replaced
--- $ Negative Number => Characters Left At The End After Replacement
--- $ 0 => Insert Instead Of Replace
*/
echo substr_replace("OneTwo", 1, 0); // 1
echo '<br>';
echo substr_replace("OneTwo", 1, 3); // One1
echo '<br>';
echo substr_replace("OneTwo", 1, 5); // OneTw1
echo '<br>';
echo substr_replace("OneTwo", 1, -1); // OneTw1
echo '<br>';
echo substr_replace("OneTwo", 2, 2); // On2
echo '<br>';
echo substr_replace("OneTwo", 2, 2, 2); // On2wo
echo '<br>';
echo substr_replace("OneTwo", 2, 1, 4); // O2o
echo '<br>';
echo substr_replace("Elzero_Web_School", "A", 7, 3); // Elzero_A_School
echo '<br>';
echo substr_replace("Elzero_Web_School", "A", 7, -1); // Elzero_Al eb_School
echo '<br>';
echo substr_replace("Elzero_Web_School", "A", 7, -3); // Elzero_Aool eb_Sch
echo '<br>';
echo substr_replace("Elzero_Web_School", "A", 7, -9); // Elzero_Aeb_School
echo '<br>';
echo substr_replace("Elzero_Web_School", "A", 7, -10); // Elzero_AWeb_School
echo '<br>';
echo substr_replace("Elzero_Web_School", "@", 1, 0); // E@lzero_Web_School
echo "<pre>";
print_r(substr_replace(["OneTwo", "ThreeFour"], 1, 0));
echo "</pre>";