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<!DOCTYPE html> <html lang="en"> <head> <title>Example of Testing Whether a Variable is Set in PHP</title> </head> <body> <?php $var1 = ''; if(isset($var1)){ echo 'This line is printed, because the $var1 is set.'; } echo "<br>"; $var2 = 'Hello World!'; if(isset($var2)){ echo 'This line is printed, because the $var2 is set.'; } echo "<br>"; // Unset the variable unset($var2); if(isset($var2)){ echo 'This line is printed, because the $var2 is set.'; } else{ echo 'This line is printed, because the $var2 is not set.'; } echo "<br>"; $var3 = NULL; if(isset($var3)){ echo 'This line is printed, because the $var3 is set.'; } else{ echo 'This line is printed, because the $var3 is not set.'; } ?> </body> </html>
