Solve Call to a member function combinestring() on a non-object - php

Question

I met a problem when Call to a member function combinestring() on a non-object.
**Index.php**
inlcude("string.php");
calldata('usa');
**string.php**
$a=new a();
funciton calldata($val){
$st1="select a from table 1 where country=".$a->combinestring($val);
return $st1;
}
**Class A**
function combinestring($abc){
Return "'".$abc."'";
}
Unknow $a->combinestring($val);
How to solve this problem.
Best Regards

Answer 1

You're getting error
Call to a member function combinestring() on a non-object
because you are calling a member function on the variable that is not an object. That means $a is not an object.
In string.php , you cannot use $a inside function definition because variable has local scope. You cannot access that object instance like that. You can however do this by using global variable.
Your string.php file should be like this:
$a=new a();
funciton calldata($val){
global $a;
$st1="select a from table 1 where country=".$a->combinestring($val);
return $st1;
}
Head to this link for more information on variable scope: http://php.net/manual/en/language.variables.scope.php

Answer 2

Use PDO.
funciton calldata($val){
$st1="select a from table 1 where country = ?";
$pdo = new PDO('host', 'user', 'pass');
$result = $pdo->prepare($st1)->execute($val);
return $result;
}
This is a lot different from what you are doing, but your a class does not escape the input to the query and that's bad.