PHP 関数で警告が発生する一般的なシナリオは何ですか?

PHP
Notice: Undefined variable: $variable

PHP
Notice: Undefined function: myFunction()

PHP
Notice: Argument 1 passed to myFunction() must be of the type string, null given

PHP
Notice: Argument 2 passed to myFunction() must be unique

PHP
Warning: fopen(filename.txt): failed to open stream: No such file or directory

PHP
<?php
$name = "John"; // 未定义变量

echo "Name: $name"; // 会触发警告
?>

PHP
<?php
function myFunction($name) {
  if (is_string($name)) {
    // do something
  }
}

myFunction(123); // 会触发警告
?>

PHP
error_reporting(0);