The differences between exit, exit (0), exit (1), exit ('0 '), exit ('1'), die and return in PHP

die(‘1’) die() and exit() All stop script execution functions ; Actually exit and die These two names point to the same function ,die() yes exit() Alias for function . This function only takes one parameter , It can be a numeric value returned by a program or a string , It is also possible to enter no parameters , The result has no return value .

Reference resources ： Although the two are the same , But there is also a slight selectivity in use .

When passed to the exit and die The value of the function is 0 when , It means to terminate the execution of the script ahead of time , Usually use exit() The name .

echo "1111"; exit(0); echo "2222";

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When the program goes wrong , You can pass it a string , It will be output on the system terminal as is , Usually use die() The name .

$fp=fopen("./readme.txt","r") or die(" Cannot open the file "); // In this case , If fopen The function is called to return a Boolean value false when ,die() The script will be terminated immediately , And print it now  // The string passed to it ,“ I can say oneortwo words before I die ”.

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alike die(‘1’) Yetong exit(‘1’) equally , Output 1

echo "begin"; die('1'); echo "end"; // Output begin1

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exit(1) No output , End procedure

echo "begin"; exit(1); echo "end"; // Output begin

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exit(0) No output , End procedure

echo "begin"; exit(0); echo "end"; // Output begin

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exit(‘0’) Output 0 And end the program

echo "begin"; exit('0'); echo "end"; // Output begin0

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exit(‘1’) Output 1 And end the program

echo "begin"; exit('1'); echo "end"; // Output begin1

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return Return value , Subsequent procedures are not implemented , Value is not output

echo "begin"; return 1; echo "end"; // Output begin,return The value of is not output to the screen , Instead, it returns to the previous layer 

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summary ：

return Is the return value

die It's a mistake that stops

exit It's a direct stop , And do not run subsequent code , exit () You can display content .

return Is the pure return value , But it will not run subsequent code

exit （0）： Run the program normally and exit the program ;

exit （1）： Abnormal operation causes the program to exit ;

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