The difference between exit () and Die () in PHP

Source: Internet
Author: User
Tags exit execution functions php session reference return string variable

This article briefly analyzes the use of PHP in the exit and die differences, there is a need for friends to see.

First, consider a question:

What does the following code show to the page?

die (123);
? >

There was a time when I thought the page would show 123, but the result told me that the answer was wrong and the page was blank!

Always do not know why, anyway not output 123, in order to let the page output 123, I modify it to the following code:

echo ' 123 ';
Die ();
? >

A piece of information on the Internet:

The difference between exit () and Die () in PHP

PHP Manual: Die () equivalent to exit ().

Description: Die () and exit () are aborted script execution functions; in fact, exit and die these two names point to the same function, die () is an alias for the exit () function. The function accepts only one parameter, either a value returned by a program or a string , or a parameter without input, and the result has no return value.

Reference: Although the two are the same, there are also subtle selectivity in the use. For example:

When passed to the exit and die functions, the value of 0 means that the execution of the script is terminated prematurely, usually with the name of exit ().

echo "1111";
Exit (0);
echo "2222";  22222 will not be output, because the program runs to exit (0), the script has been terminated prematurely, "immediately expired."

When an error occurs, you can pass a string to it, which is output to the system terminal, usually using the name Die ().

$FP =fopen ("./readme.txt", "R") or Die ("Cannot open the file");
In this case, if the fopen function is invoked to return the Boolean value false, Die () will immediately terminate the script and print
//Pass it to the string immediately, "one or two words before death."

Back to the previous topic, why does the following code not output 123 to the page?

die (123);
or exit (123);
? >

Own summary:

1, function, die () is equivalent to exit ();

2, PHP has a variety of ways to run, can be the form of a Web site, but also script form (do not require a Web server).

When PHP is running as a script, it is recommended to use Exit ():

For example, Bash the Shell scripting language, when it stops running, terminates the script with the exit () function and allows the output point content to be in the operating environment (typically stored in a global variable), but the output can only be a number , indicating " The end state of the command.

Related Reference Links:

In other words, exit (123) simply outputs a running state of 123 instead of actually outputting 123 to the console . If you want to output 123 to the console , the code must be changed to the following form:

exit (' 123 ');
? >

When PHP is running as a Web site, it is recommended to use Die ():

But at this point die (number), there is no meaning, because it will not output the number of strings to the page, that is, if you want to let the page terminate and output the number, you have to change to the following form

die (' 123 ');
? >

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