.: iceis' Blog :.

$var = "var";
echo " $var ";
echo " '$var' ";
echo ' $var '
echo ' "$var" '

$test[a] = "A";

echo " $test[a] ";
echo ' $test[a] '
echo " '$test[a]'";
echo ' "$test[a]" '
=====================
> $var = "var";
> echo " $var ";
var
> echo " '$var' ";
'var'
> echo ' $var '
$var
> echo ' "$var" '
"$var"
> $test[a] = "A";
> echo " $test[a] ";
A
> echo ' $test[a] '
$test[a]
> echo " '$test[a]'";
'A'
> echo ' "$test[a]" '
"$test[a]"

conclusion: ''會把內容當成字串，""會試著把字串中有包含變數的內容印出