Checking for undefined variables in a function php - php

Question

So I've been trying to devise a function that will echo a session variable only if it is set, so that it wont create the 'Notice' about an undefined variable. I am aware that one could use:
if(isset($_SESSION['i'])){ echo $_SESSION['i'];}
But it starts to get a bit messy when there are loads (As you may have guessed, it's for bringing data back into a form ... For whatever reason). Some of my values are also only required to be echoed back if it equals something, echo something else which makes it even more messy:
if(isset($_SESSION['i'])){if($_SESSION['i']=='value'){ echo 'Something';}}
So to try and be lazy, and tidy things up, I have tried making these functions:
function ifsetecho($variable) {
if(!empty($variable)) {
echo $variable;
}
}
function ifseteqecho($variable,$eq,$output) {
if(isset($variable)) {
if($variable==$eq) {
echo $output;
}
}
}
Which wont work, because for it to go through the function, the variable has to be declared ...
Has anyone found a way to make something similar to this work?

Answer 1

maybe you can achieve this with a foreach?
foreach ($_SESSION as $variable)
{function ifseteqecho($variable,$eq,$output) {
if($variable==$eq) {
echo $output;
}
else echo $variable;
}
}
now this will all check for the same $eq, but with an array of corresponding $eq to $variables:
$equiv = array
('1'=>'foo',
'blue'=>'bar',);
you can check them all:
foreach ($_SESSION as $variable)
{function ifseteqecho($variable,$equiv) {
if(isset($equiv[$variable])) {
echo $equiv[$variable];
}
else {
echo $variable;
}
}
}

Answer 2

Something like this?, you could extend it to fit your precise needs...
function echoIfSet($varName, array $fromArray=null){
if(isset($fromArray)){
if(isset($fromArray[$varName])&&!empty($fromArray[$varName])){
echo $fromArray[$varName];
}
}elseif(isset($$varName)&&!empty($$varName)){
echo $$varName;
}
}

Answer 3

You may use variable variables:
$cat = "beautiful";
$dog = "lovely";
function ifsetecho($variable) {
global $$variable;
if(!empty($$variable)){
echo $$variable;
}
}
ifsetecho("cat");
echo "<br/>";
ifsetecho("dog");
echo "<br/>";
ifsetecho("elephant");
UPDATE: With a rather complex code I’ve managed to meet your requirements:
session_start();
$cat = "beautiful";
$dog = "lovely";
$_SESSION['person']['fname'] = "Irene";
function ifsetecho($variable){
$pattern = "/([_a-zA-Z][_a-zA-Z0-9]+)".str_repeat("(?:\\['([_a-zA-Z0-9]+)'\\])?", 6)."/";
if(preg_match($pattern, $variable, $matches)){
global ${$matches[1]};
if(empty(${$matches[1]})){
return false;
}
$plush = ${$matches[1]};
for($i = 2; $i < sizeof($matches); $i++){
if(empty($plush[$matches[$i]])){
return false;
}
$plush = $plush[$matches[$i]];
}
echo $plush;
return true;
}
return false;
}
ifsetecho("cat");
echo "<br/>";
ifsetecho("dog");
echo "<br/>";
ifsetecho("elephant");
echo "<br/>";
ifsetecho("_SESSION['person']['fname']");
echo "<br/>";
ifsetecho("_SESSION['person']['uname']");
echo "<br/>";