PHP Programming: Introducing Common File Operations_PHP Tutorial

PHP It is very convenient to handle files and directories on the local server, but sometimes permissions and path-related problems may occur.

1. Open the file

<ol class="dp-c">
<li class="alt"><span><span>resource </span><span class="func">fopen</span><span> ( string filename, string mode [, bool use_include_path [, resource zcontext]] )  </span></span></li>
<li>
<span class="vars">$handle</span><span> = </span><span class="func">fopen</span><span>(filename,mode)</span><span class="comment">//打开文件，返回代表此文件的资源的句柄</span><span> </span>
</li>
</ol>

The file name can use relative path or absolute path or network Protocol mode, open mode has rr+ww+aa+xx+b

If you do not specify the 'b' flag when operating binary files, you may encounter some strange problems, including corrupted image files and Weird question about the rn character.

For portability reasons, it is strongly recommended to always use the 'b' flag when opening files with fopen().

The following are several ways to open files

<ol class="dp-c">
<li class="alt"><span><span class="vars">$fp</span><span> = @</span><span class="func">fopen</span><span>(</span><span class="string">'log.txt'</span><span>,</span><span class="string">"rb"</span><span>);  </span></span></li>
<li>
<span class="vars">$fp</span><span> = @</span><span class="func">fopen</span><span>(</span><span class="string">'../log.txt'</span><span>,</span><span class="string">"rb"</span><span>);  </span>
</li>
<li class="alt">
<span class="vars">$fp</span><span> = @</span><span class="func">fopen</span><span>(</span><span class="string">"http://www.runer.com.cn/default.htm"</span><span>,</span><span class="string">"rb"</span><span>);</span>
</li>
<li class="alt"><span>//还可以使用ftp和ghoper等协议，必须启用php.ini文件中的allow_url_fopen选项 </span></li>
</ol>

<ol class="dp-c">
<li class="alt"><span><span class="vars">$filename1</span><span> = </span><span class="string">"userinfo.txt"</span><span>;</span><span class="comment">//目录下或include_path中存在这个文件 </span><span> </span></span></li>
<li>
<span class="vars">$filename2</span><span> = </span><span class="string">"test.txt"</span><span>;</span><span class="comment">//目录下或include_path并不存在这个文件 </span><span> </span>
</li>
<li class="alt">
<span class="vars">$resource1</span><span> = </span><span class="func">fopen</span><span>(</span><span class="vars">$filename1</span><span>,</span><span class="string">"rb"</span><span>);  </span>
</li>
<li>
<span>@</span><span class="vars">$resource2</span><span> = </span><span class="func">fopen</span><span>(</span><span class="vars">$filename2</span><span>,</span><span class="string">"rb"</span><span>);</span><span class="comment">//因为目录中不存在这个文件，并且并未使用或include_path寻找包含文件所在路径则此操作会报错,使用错误抑制符@可以迫使浏览器不输出错误信息 </span><span> </span>
</li>
<li class="alt">
<span class="keyword">if</span><span>(</span><span class="vars">$resource1</span><span>)  </span>
</li>
<li>
<span class="func">echo</span><span> </span><span class="string">"打开文件{$filename1}成功"</span><span>;  </span>
</li>
<li class="alt">
<span class="keyword">if</span><span>(!@</span><span class="func">fopen</span><span>(</span><span class="vars">$filename2</span><span>,</span><span class="string">"r"</span><span>))  </span>
</li>
<li>
<span class="func">echo</span><span> </span><span class="string">"打开文件{$filename2}不成功"</span><span>; </span>
</li>
</ol>

Output result: The file userinfo.txt was opened successfully

2. After using the file, you must explicitly tell PHP that the file has been used and let the operating system ensure that all the contents of the file are correctly removed from the buffer. Flush to the hard disk

Use fclose() to close the file,

<ol class="dp-c"><li class="alt"><span><span>bool fclose ( resource handle )</span><span class="comment">//关闭一个已打开的文件指针 </span><span> </span></span></li></ol>

3. Read the file, the mode parameter of the fopen function allows reading Fetch, PHP provides several functions to read data from files

string fgets (int handle [, int length]) reads a line from the file pointer. Trying fgets on a binary file will produce an invalid Prediction result

If the length is not specified, 1K data will be read by default, and it will stop after encountering a newline character (included in the return value), EOF or length - 1 byte has been read

string fgetss ( resource handle [, int length [, string allowable_tags]] ) reads a line from the file pointer and filters out HTML tags

fgetc() reads a single character

fread( ) Read arbitrary binary data

Code part:

<ol class="dp-c">
<li class="alt"><span><span class="vars">$handle</span><span> = </span><span class="func">fopen</span><span> (</span><span class="string">"test.jpg"</span><span>, </span><span class="string">"rb"</span><span>);  </span></span></li>
<li>
<span class="vars">$c</span><span>;  </span>
</li>
<li class="alt">
<span class="keyword">while</span><span> (!</span><span class="func">feof</span><span>(</span><span class="vars">$handle</span><span>)) {  </span>
</li>
<li>
<span class="vars">$contents</span><span> .= @</span><span class="func">fread</span><span>(</span><span class="vars">$handle</span><span>, 8192);</span><span class="comment">//循环读取并将其合并为一个大块文件 </span><span> </span>
</li>
<li class="alt"><span>}  </span></li>
<li>
<span>fclose(</span><span class="vars">$handle</span><span>); </span>
</li>
</ol>

4. Determine the status of file reading

Each file handle has a file pointer, or a cursor that indicates where in the file the next operation will occur. According to the mode parameter of the fopen function

the file pointer is initially located at the beginning of the file (0), or the file The end of

feof() can determine whether the file has reached the end (the function returns TRUE after reaching the end) The

filesize() function returns the size of the file 5. Write the file

fwrite() function executes file writing

Code part:

<ol class="dp-c">
<li class="alt"><span><span class="vars">$filename</span><span> = </span><span class="string">'test.txt'</span><span>;  </span></span></li>
<li>
<span class="vars">$somec</span><span>;   </span>
</li>
<li class="alt">
<span class="comment">// 首先我们要确定文件存在并且可写。 </span><span> </span>
</li>
<li>
<span class="keyword">if</span><span> (</span><span class="func">is_writable</span><span>(</span><span class="vars">$filename</span><span>)) {  </span>
</li>
<li class="alt">
<span class="comment">// 在这个例子里，我们将使用添加模式打开$filename， </span><span> </span>
</li>
<li>
<span class="comment">// 因此，文件指针将会在文件的开头， </span><span> </span>
</li>
<li class="alt">
<span class="comment">// 那就是当我们使用fwrite()的时候，$somecontent将要写入的地方。 </span><span> </span>
</li>
<li>
<span class="keyword">if</span><span> (!</span><span class="vars">$handle</span><span> = </span><span class="func">fopen</span><span>(</span><span class="vars">$filename</span><span>, </span><span class="string">'a'</span><span>)) {  </span>
</li>
<li class="alt">
<span class="func">echo</span><span> </span><span class="string">"不能打开文件 $filename"</span><span>;  </span>
</li>
<li>
<span class="func">exit</span><span>;  </span>
</li>
<li class="alt"><span>}  </span></li>
<li>
<span class="comment">// 将$somecontent写入到我们打开的文件中。 </span><span> </span>
</li>
<li class="alt">
<span class="keyword">if</span><span> (fwrite(</span><span class="vars">$handle</span><span>, </span><span class="vars">$somecontent</span><span>) === FALSE) {  </span>
</li>
<li>
<span class="func">echo</span><span> </span><span class="string">"不能写入到文件 $filename"</span><span>;  </span>
</li>
<li class="alt">
<span class="func">exit</span><span>;  </span>
</li>
<li><span>}  </span></li>
<li class="alt">
<span class="func">echo</span><span> </span><span class="string">"成功地将 $somecontent 写入到文件$filename"</span><span>;  </span>
</li>
<li>
<span>fclose(</span><span class="vars">$handle</span><span>);  </span>
</li>
<li class="alt">
<span>} </span><span class="keyword">else</span><span> {  </span>
</li>
<li><span>}  </span></li>
<li class="alt">
<span class="func">echo</span><span> </span><span class="string">"文件 $filename 不可写"</span><span>; </span>
</li>
</ol>

Output result:

Successfully adds these words to the file Write to file test.txt

For binary data, the third parameter must be specified, which contains the number of data bytes written to disk

<ol class="dp-c"><li class="alt"><span><span class="vars">$result</span><span> = @fwrite(</span><span class="vars">$fp</span><span>,</span><span class="vars">$binary_data</span><span>,mb_strlen(</span><span class="vars">$binary_data</span><span>,</span><span class="string">'8bit'</span><span>));  </span></span></li></ol>

6. File permissions and other information

• is_readable()//Judge whether the file is readable
• is_writeable()//Judge whether the file is writable
• is_writable()//Determine whether the file is writable
• fileperms()//Determine the permissions of the file (UNIX-style file permission test function)
• file_exists()//Whether This file exists
• fileowner()//Determine the user to which the file belongs
• filegroup()//Determine the group to which the file belongs

7. Delete and redo Name the file

• unlink()//Delete the file
• rename()//Rename the file

8. Visit Directory

It is recommended to use the forward slash "/" for directory access, which is compatible with windows and unix systems

• basename()//returns the file name without path information
• dirname()//Returns the directory part of the file name
• realpath()//Accepts relative paths and returns the absolute path of the file
• pathinfo()//Extracts the given The directory name, base file name and extension of the path
• opendir()//Open the directory and return the resource handle
• readdir()//Read the directory entry
• rewinddir( )//Return the read pointer to the beginning
• closedir()//Close the read handle
• chdir()//Change the current working directory during the execution of the current script
• mkdir()//Create directory
• rmdir() Delete directory

I hope the above content introduces the common file operation methods in the eight middle schools and is helpful to you.

http://www.bkjia.com/PHPjc/445756.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/445756.htmlTechArticlePHP is very convenient to process files and directories on the local server, but sometimes there are permissions and path related issues. question. 1. Open the file resource fopen (stringfilename,stringmode[,...