A case study of the difference between PHP functions isset and empty

A case study of the difference between PHP functions Isset () and Empty ()

1.? PHP error_reporting (e_all);
2 echo ' <B> undefined $var</b><br> ';
3 echo "Isset test:<br>";
4 if (Isset ($var))
5 {
6 echo ' variable $var existence!<br> ';
7}
8
9
echo "Empty test:<br>";
One if (empty ($var)) {
The value of ECHO ' variable $var is null <Br> ';
13}
Or else
15 {
The value of the Echo ' variable $var is not null <Br> ';
17}
18
echo "Variable direct test:<br>";
if ($var) {
Echo ' variable $var exists!<br> ';
22}
% Else {
echo ' variable $var does not exist!<br> ';
25}
26
Echo '----------------------------------<br> ';
echo ' <B> $var = \ ' </b><Br> ';
echo "Isset test:<br>";
$var = ';
if (Isset ($var))
32 {
The echo ' variable $var exist!<br> ';
34}
35
36
Panax notoginseng echo "Empty test:<br>";
if (empty ($var)) {
The value of the $var variable is null <Br> ';
40}
Or else
42 {
The value of the Echo ' variable $var is not null <Br> ';
44}
45
The echo "Variable direct test:<br>";
if ($var) {
The echo ' variable $var exist!<br> ';
49}
Or else {
No echo ' variable $var not exist!<br> ';
52}
Echo '----------------------------------<br> ';
echo ' <B> $var = 0</b><br> ';
Echo ' isset test:<br> ';
$var = 0;
if (Isset ($var))
58 {
$var echo ' variable exists!<br> ';
60}
61
62
The echo "Empty test:<br>";
if (empty ($var)) {
The value of $var ' variable is null <Br> ';
66}
Or else
68 {
The value of $var echo ' variable is not null <Br> ';
70}
71
The "Variable direct test:<br>";
if ($var) {
The "Variable $var exists!<br>";
75}
Or else {
The $var echo ' variable does not exist!<br> ';
78}
Echo '----------------------------------<br> ';
80
Bayi echo ' <B> $var = Null</b><br> ';
The echo ' isset test:<br> ';
$var = null;
if (Isset ($var))
85 {
The echo ' variable $var exist!<br> ';
87}
88
89
The echo "Empty test:<br>";
(Empty ($var)) {
The value of the $var echo ' variable is null <Br> ';
93}
Or else
95 {
The value of ECHO ' variable $var is not null <Br> ';
97}
98
echo "Variable direct test:<br>";
if ($var) {
Echo ' variable $var exists!<br> ';
102}
Or else {
The echo ' variable $var does not exist!<br> ';
105}
"----------------------------------<br>";
107
108
109 echo ' <B> $var = ' php ' </b><Br> ';
The echo ' isset test:<br> ';
$var = "PHP";
112 if (Isset ($var))
113 {
114 echo ' variable $var exists!<br> ';
115}
116
117
118 echo "Empty Test:<br>";
119 if (empty ($var)) {
The value of the Echo ' variable $var is null <Br> ';
121}
122 Else
123 {
124 echo ' variable $var value is not null <Br> ';
125}
126
127 echo "Variable direct test:<br>";
128 if ($var) {
129 echo ' variable $var exists!<br> ';
130}
131 else {
132 echo ' variable $var does not exist!<br> ';
133