[PHP] Return to the basics (IO stream), return to the io_PHP tutorial

[PHP] Return to the basics (IO stream), return to io

IO stream is used to handle data transfer between devices

java operates on data through streams

javaObjects used to operate streams are in the IO package

Streams are divided into two types according to operation data: byte stream and character stream

Streams are divided into: input stream, output stream

Character stream

Abstract base class: Reader Writer

File operation, write

Get the FileWriter object, new comes out, construction parameters: String file name ; At this time, a file will be created in the specified directory. If it already exists, it will be overwritten; this method will throw IOExceptionException

Call the FileWriter object's write() method to write the string into the stream, parameters: StringString

Call the FileWriter object's flush() method to refresh the stream

        FileWriter fw=<span>new</span> FileWriter("test.txt"<span>);
        fw.write(</span>"hello3"<span>);
        fw.close();</span><span>//</span><span>刷新并关闭</span>

File operation, read

Get the FileReader object, new come out, construction parameters: String file name

Call the read() method of the FileReader object to return the read length. If it reaches the end, it will return -1, parameter: char[] Character array

while loop reading, condition: if the read length is not -1

Combined string

        FileReader fr=<span>new</span> FileReader("test.txt"<span>);
        </span><span>char</span>[] buf=<span>new</span> <span>char</span>[2<span>];
        </span><span>int</span> len=0<span>;
        StringBuilder sb</span>=<span>new</span><span> StringBuilder();
        </span><span>while</span>((len=fr.read(buf))!=-1<span>){
            sb.append(</span><span>new</span> String(buf,0<span>,len));
        }
        System.out.println(sb.toString());</span>

PHP version, file operation, writing

Call the function fopen() to open the file and obtain the file object, parameters: String file name, "w" is written, if the file does not exist, it will be created

Call the fwrite() method to write directly to the file. Parameters: file object, String string

Call the fclose() method to close the stream, parameters: file object

<span>$file</span>=<span>fopen</span>("test.txt","w"<span>);
</span><span>fwrite</span>(<span>$file</span>,"hello"<span>);
</span><span>fclose</span>(<span>$file</span>);

File operation, read

Call the function fopen() to open the file and get the file object, parameters: String file name, ”r” reads

Call the function fread() to get the string of String, parameters: fileObject, read length

while loop reading, condition: not to the end of the file, feof($file) is not true

Concatenate strings

<span>$file</span>=<span>fopen</span>("test.txt","r"<span>);
</span><span>$str</span>=""<span>;
</span><span>while</span>(!<span>feof</span>(<span>$file</span><span>)){
    </span><span>$str</span>.=<span>fread</span>(<span>$file</span>, 1<span>);
}

</span><span>echo</span> <span>$str</span><span>;
</span><span>fclose</span>(<span>$file</span>);