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<meta charset="UTF-8">
<title>PHP Function</title>
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function sum($value1, $value2 = 0, $value3 = 0)
{
return $value1 + $value2 + $value3;
}
echo sum(1, 2, 3)."<br>";
echo sum(1, 2)."<br>";
echo sum(1);
//echo sum(); // 오류가 발생함.
</body>
</html>