PHP common functions 2--file operations_PHP tutorial

php common functions 2--file operations

1. File type
1.filetype()
Get the file type function, the parameter is a string (path + file name)
The return value is a string, file (normal file), dir (directory) or unknown (unknown file)
2.is_file() is_dir()
Determine whether it is this type and return a Boolean value
2. File attributes (the following function parameters are all file names)
1.file_exists() Check whether the file or directory exists
2.filesize() Get the file size, return false if an error occurs
3.is_readable( ) Whether it is readable
4.is_writable() Whether it is writable
5.is_executable() Whether it is executable
6.filectime() Get the creation time
7.filemtime() Get the modification time
8.fileatime() Get access time
9.stat() Get most attribute values ​​of the file
10.clearstatcache() Clear the file information cached by PHP
3. Parse directory
1 .basename(path,[suffix]) returns the file name part of the path. The second parameter is the extension (such as "php" or ".php"). If given, there will be no extension in the return value
2.dirname(path) returns the directory name after removing the file name
3.pathinfo() returns an associative array, including dirname (directory name), basename (basic name), extension (extension name)
Four , Traverse the directory
1.opendir() opens the specified directory and returns a directory handle that can be used by other directory functions. Failure returns false
2.readdir() reads the specified directory, the parameter is the directory handle, returns a file name at the current directory pointer position, and moves the pointer one position back. No more files return false
3.closedir() Close the specified directory, the parameter is the directory handle
4.rewinddir() Rewind the directory handle, the parameter is the directory handle, reset the directory pointer to the beginning
5. Create and delete directories
1.mkdir() Create a new directory, the parameter is the directory name
2.rmdir() Delete a directory. Only empty directories can be deleted. If it is not empty, you must first Enter the directory and delete the files in it using the unlink() function
6. Copy or move the directory
1. Copy: There is no specific function in php. You must first create a new directory mkdir(), and then use the copy() function to copy per file.
2. Move: first copy, then delete the original directory
7. File opening and closing
1.fopen(filename,mode[,use_include_path[,zcontext]]) opens the file, the parameter is the file name, File mode, the third parameter is optional, setting it to 1 will cause PHP to consider the path specified in the configuration directive include_path, the fourth parameter is optional, the setting allows the file name to start with the protocol name, such as http://. Returns the file pointer, returns false on failure.
Mode summary:
r read-only
r+ read-write
w write-only (if the file exists, delete the original data, if the file does not exist, create the file)
w+ read-write ( Same as w)
x write (the file exists, return false, create the file if it does not exist, only local)
x+ read and write (same as x)
a write (the pointer points to the end of the file, the file does not exist then create)
a+ write (same as a)
b binary mode
t text mode
2.fclose() close
8. Manipulate file content
1.fwrite(handle ,string[,length]) writes a string. nr is the line ending character. Returns the number of characters written, and returns false on failure.
2.fread(handle,length) Read the open file
3.file_get_contents() Read the file into a string
4.fgets(handle[ ,length]) Returns a line
5.fgetc() Returns characters
6.file() Read the file into an array, each line is an element.
7.readfile() reads a file and outputs it to the output buffer
8.feof() determines whether the end of the file is reached, if so it returns true
9.file_get_contents()
10. Access Remote files: Activate the "allow_url_fopen" option in the configuration file, and the set_time_limit() function controls the program running time to avoid timeout errors.
9. Move the file pointer
1.ftell(handle) Return the current position of the file pointer
2.fseek(handle,offset[,whence]) Move the file pointer to the position specified by the offset parameter.
Parameter three: SEEK_CUR current position plus the second parameter to add the provided byte;
SEEK_END EOF plus offset byte, at this time, offset must be a negative value;
SEEK_SET offset byte , the same effect as without this parameter;
returns 0 on success and -1 on failure. If opened with a or a+, it is always appended, regardless of the file pointer position.
3.rewind(handle) Move to file switch
10. File locking mechanism (to prevent multiple users from accessing the same file at the same time causing file confusion)
1.flock(handle,operation[,&wouldblock]) file locking Operation, parameter two: LOCK_SH shared lock, used when reading data; LOCK_EX exclusive lock, used when writing data; LOCK_UN releases the lock; LOCK_NB additional lock to prevent blocking when locking. Parameter three: When set to 1, other processes will be blocked during the lock period.
10. File copying, deletion, etc.
1.copy (source file, destination file) Copy
2.unlink (target file) Delete file
3.ftruncate (target file resource, interception length) Truncate the file to the specified length
4.rename (old file name, new file name) Rename the file or directory
11. File upload and download
1. Global array $_FILES
$_FILES ["myfile"]["name"] Original name, including extension
$_FILES["myfile"]["size"] Uploaded file size, unit is bytes
$_FILES["myfile"]["tmp_name"] Temporary file name after upload
$_FILES["myfile"]["error"]0: Success; 1: The size exceeds the PHP configuration file limit; 2: The size exceeds the form Limitations; 3: Incomplete file upload; 4: No files uploaded
$_FILES["myfile"]["type"] Get the MIME type of the uploaded file
2.is_uploaded_file() Determine whether it is uploaded through HTTPPOST
3.move_uploaded_file() moves the uploaded file from the temporary location to the new location
4.Download header information processing
header('Content-Type:image/gif'); MIME type
header('Content-Disposition:attachment;filename="test.gif"');Header information, attachment and file name
header('Content-Length:3390'); Size
readfile('test.gif ');

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