Copy the code The code is as follows:
//sprintf() function, the return value is the formatted string
string sprintf ( string $format [, mixed $args [, mixed $ ... ]] )
$y = 11;
$m = 3;
$d = 9;
$date = sprinf('%04d-%02d-%02d', $y, $m ,$d) ;
echo $date; //0011-0
//printf() function, the return value is the formatted string length
int printf ( string $format [, mixed $args [, mixed $... ]] )
$num = 3.14;
printf("Character padding %'#6.2s", $num); //##3.14
//The character length is 6, with 2 after the dot, less than 6 digits, # padding
The difference between sprintf() and printf()
The syntax and format are the same, but the return value is different
Definition and usage
The sprintf() function writes the formatted string into a variable.
Syntax
sprintf(format,arg1,arg2,arg++)
Parameters | Description |
---|---|
format | Required. Convert format. |
arg1 | Required. Specifies the parameters to be inserted at the first % sign in the format string. |
arg2 | Optional. Specifies the parameter to be inserted into the format string at the second % sign. |
arg++ | Optional. Specifies the parameters to be inserted into the format string at the third, fourth, etc. % symbols. |
Description
Parameter format is the converted format, starting with the percent sign ("%") and ending with the conversion character. Possible format values below:
- %% - Returns the percent symbol
- %b - binary number
- %c - character according to ASCII value
- %d - signed decimal number
- %e - Continuous counting method (such as 1.5e+3)
- %u - unsigned decimal number
- %f - floating point number (local settings aware)
- %F - floating point number (not local settings aware)
- %o - octal number
- %s - string
- %x - Hexadecimal number (lowercase letters)
- %X - Hexadecimal number (capital letters)
arg1, arg2, ++, etc. are inserted into the main string at the percent sign (%) symbol. This function is executed step by step. At the first % sign, insert arg1, at the second % sign, arg2, and so on.
Example
Example 1
Copy code The code is as follows:
$str = "Hello";
$number = 123;
$txt = sprintf("%s world. Day number %u",$str,$number);
echo $txt;
?>
Output:
Hello world. Day number 123
Example 2
Copy the code The code is as follows:
< ;?php
$number = 123;
$txt = sprintf("%f",$number);
echo $txt;
?>
Output:
123.000000
Example 3
Copy code The code is as follows:
$number = 123;
$txt = sprintf("With 2 decimals: %1$.2f
With no decimals: %1$u",$number );
echo $txt;
?>
Output:
With 2 decimals: 123.00
With no decimals: 123
For more details, please refer to http://www.jb51.net/w3school/php/func_string_sprintf. htm
The above has introduced the use case analysis of the PHP sprintf function, including the relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.

The main advantages of using database storage sessions include persistence, scalability, and security. 1. Persistence: Even if the server restarts, the session data can remain unchanged. 2. Scalability: Applicable to distributed systems, ensuring that session data is synchronized between multiple servers. 3. Security: The database provides encrypted storage to protect sensitive information.

Implementing custom session processing in PHP can be done by implementing the SessionHandlerInterface interface. The specific steps include: 1) Creating a class that implements SessionHandlerInterface, such as CustomSessionHandler; 2) Rewriting methods in the interface (such as open, close, read, write, destroy, gc) to define the life cycle and storage method of session data; 3) Register a custom session processor in a PHP script and start the session. This allows data to be stored in media such as MySQL and Redis to improve performance, security and scalability.

SessionID is a mechanism used in web applications to track user session status. 1. It is a randomly generated string used to maintain user's identity information during multiple interactions between the user and the server. 2. The server generates and sends it to the client through cookies or URL parameters to help identify and associate these requests in multiple requests of the user. 3. Generation usually uses random algorithms to ensure uniqueness and unpredictability. 4. In actual development, in-memory databases such as Redis can be used to store session data to improve performance and security.

Managing sessions in stateless environments such as APIs can be achieved by using JWT or cookies. 1. JWT is suitable for statelessness and scalability, but it is large in size when it comes to big data. 2.Cookies are more traditional and easy to implement, but they need to be configured with caution to ensure security.


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