File Access

file_get_contents()
Want to read the whole file

readfile()
Want to output the entire contents of the file

file()
want to read line-by-line text file as an array

fopen() + fread()
Want to read the file byte by byte

SplFileObject class
want to read CSV

SplFileObject class
want to operate object-oriented

サンプルのjsonデータを使ってみます。

{
    "glossary": {
        "title": "example glossary",
		"GlossDiv": {
            "title": "S",
			"GlossList": {
                "GlossEntry": {
                    "ID": "SGML",
					"SortAs": "SGML",
					"GlossTerm": "Standard Generalized Markup Language",
					"Acronym": "SGML",
					"Abbrev": "ISO 8879:1986",
					"GlossDef": {
                        "para": "A meta-markup language, used to create markup languages such as DocBook.",
						"GlossSeeAlso": ["GML", "XML"]
                    },
					"GlossSee": "markup"
                }
            }
        }
    }
}

$json = file_get_contents(__DIR__ . '/sample.json');
if($json === false){
	echo ('file not found.');
} else {
	$data = json_decode($json, true);
	var_dump($data);
}

file_get_contents() は、使用頻度高いです。