PHP basic functions

Introduction: This is a detailed page for PHP basic functions. It introduces the related knowledge, skills, experience, and some PHP source code.

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Define Constants

Define ('appconfig', 'pluaconfig ');

Returns a constant.

Echo constant ('appconfig'). "\ n ";

The constant cannot be defined twice.

Initialize variable value

Ini_set ('display _ errors ', 1 );

Obtain the variable value.

Echo ini_get ('display _ errors '). "\ n ";

PHP

Ob_start ();

Related functions:

1. Flush: refresh the buffer content and output it.

Function Format: flush ()

Note: This function is frequently used and highly efficient.

2. ob_start: Open the output buffer.

Function Format: void ob_start (void)

Note: When the buffer zone is activated, all non-file header information from the PHP program is not sent, but stored in the internal buffer zone. To output the buffer content, you can use ob_end_flush () or flush () to output the buffer content.

3. ob_get_contents: returns the content of the internal buffer.

Usage: String ob_get_contents (void)

Note: This function returns the content in the Current Buffer. If the output buffer is not activated, false is returned.

4. ob_get_length: return the length of the internal buffer.

Usage: int ob_get_length (void)

Note: This function returns the length of the Current Buffer. It is the same as ob_get_contents if the output buffer is not activated. Returns false.

5. ob_end_flush: sends the content of the internal buffer to the browser and closes the output buffer.

Usage: void ob_end_flush (void)

Note: This function sends the content of the output buffer (if any ).

6. ob_end_clean: Delete the content of the internal buffer and disable the internal buffer.

Usage: void ob_end_clean (void)

Note: This function will not output the content of the internal buffer but delete it!

7. ob_implicit_flush: enable or disable absolute refresh

Usage: void ob_implicit_flush ([int flag])

Note: Anyone who has used Perl knows the meaning of $ | = x. This string can enable/disable the buffer, while the ob_implicit_flush function is the same as that. The buffer is disabled by default, after the absolute output is enabled, each Script output is directly sent to the browser, and you do not need to call flush ()

Example:

<? PHP

Ob_start ();

Echo "Hello \ n ";

$ C = ob_get_contents ();

Ob_end_flush ();

Echo "cache =". $ C;

?>

Output:

Hello

Cache = Hello

$ T0 = 0;

$ S0 = 0;

$ T1 = 0;

$ S1 = 0;

$ T2 = 0;

$ S2 = 0;

$ T3 = 0;

$ S3 = 0;

If (ob_get_level ()){

$ T0 = 1;

$ S0 = ob_get_level ();

}

Ob_start ();

If (ob_get_level ()){

$ T1 = 1;

$ S1 = ob_get_level ();

}

Ob_start ();

If (ob_get_level ()){

$ T2 = 1;

$ S2 = ob_get_level ();

}

Ob_start ();

If (ob_get_level ()){

$ T3 = 1;

$ S3 = ob_get_level ();

}

Ob_end_flush ();

Ob_end_flush ();

Ob_end_flush ();

Echo "T0 =". $ t0. "\ n ";

Echo "S0 =". $ s0. "\ n ";

Echo "T1 =". $ T1. "\ n ";

Echo "S1 =". $ S1. "\ n ";

Echo "T2 =". $ t2. "\ n ";

Echo "S2 =". $ s2. "\ n ";

Echo "T3 =". $ T3. "\ n ";

Echo "S3 =". $ S3. "\ n ";

Output:

T0 = 0

S0 = 0

T1 = 1

S1 = 1

T2 = 1

S2 = 2

T3 = 1

S3 = 3

Die ()

The function outputs a message and exits the current script.

This is the alias of the exit () function.

Syntax

Die (Status)

Parameter description

Status is required. Specifies the message or status number written before exiting the script. The Status Number is not written to the output.

Description

If status is a string, the function outputs the string before exiting.

If status is an integer, this value is used as the exit status. The exit status ranges from 0 to 254. Exit status 255 is retained by PHP and will not be used. Status 0 is used to successfully terminate the program.

File_exists ()

Whether the file exists,

Is_readable ()

Whether the file is readable

Realpath ()

Absolute path

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