PHPのシステム機能とその使い方を詳しく解説

$str = "Hello World!";
echo strlen($str); // 输出 12

$str = "Hello World!";
echo substr($str, 0, 5); // 输出 "Hello"

$str = "Hello World!";
echo strpos($str, "World"); // 输出 6

$str = "Hello World!";
echo str_replace("World", "PHP", $str); // 输出 "Hello PHP!"

$arr = array(1, 2, 3, 4, 5);
echo count($arr); // 输出 5

$arr = array(1, 2, 3);
array_push($arr, 4, 5);
print_r($arr); // 输出 Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 )

$arr = array(1, 2, 3);
array_pop($arr);
print_r($arr); // 输出 Array ( [0] => 1 [1] => 2 )

$arr1 = array(1, 2, 3);
$arr2 = array(4, 5, 6);
print_r(array_merge($arr1, $arr2)); // 输出 Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 )

$fp = fopen("test.txt", "r");

$fp = fopen("test.txt", "r");
while(!feof($fp)) {
  echo fgets($fp). "
";
}
fclose($fp);

$fp = fopen("test.txt", "w");
fwrite($fp, "Hello World!");
fclose($fp);

$str = file_get_contents("test.txt");
echo $str;

echo date("Y-m-d H:i:s"); // 输出 "2022-01-01 00:00:00"

echo time(); // 输出当前时间的Unix时间戳

echo strtotime("2022-01-01"); // 输出 Unix时间戳

echo mktime(0, 0, 0, 1, 1, 2022); // 输出 Unix时间戳

$str = "Hello World!";
if(preg_match("/World/i", $str)) {
  echo "Match found!";
} else {
  echo "Match not found.";
}

$str = "Hello World!";
echo preg_replace("/World/i", "PHP", $str);

$str = "Hello,PHP,World!";
print_r(preg_split("/,/", $str));

$str = "Hello World!";
echo md5($str);

$str = "Hello World!";
echo sha1($str);

$str = "Hello World!";
echo base64_encode($str);

$str = "SGVsbG8gV29ybGQh";
echo base64_decode($str);