Create dynamic text file with php function - php

Question

So I need to create a dynamic text file based on the name of a variable in php (ex: dynamicName.txt). I then need to write other variables in the file.
$testVar = "test.txt";
function sendCalc(){
global $testVar;
$objCalcTxt = ("C:\\xampp\\htdocs\\test.new\\upload\\$testVar");
$fp = fopen($objCalcTxt, 'x');
fwrite($fp, "Test\n");
fclose($fp);
When I do the above, the file is created with no problem, and all the data is written successfully. However, this is not a dynamic file name.
$objName = "dynamicName";
$ext = ".txt"
$dynamicNameTxt = $objName.$ext;
function sendCalc(){
global $objName;
global $ext;
global $dynamicNameTxt;
$objCalcTxt = ("C:\\xampp\\htdocs\\test.new\\upload\\$dynamicNameTxt");
$fp = fopen($objCalcTxt, 'x');
fwrite($fp, "Test\n");
fclose($fp);
When I try to concatenate the variable that contains the dynamic file name ($objName), with the $ext var, it does not want to create the file.
I echoed the $dynamicName var and it returns dynamicName.txt, so why doesn't this work with fopen. Essentially it has to be a problem with the concatenation right? If so, can I either concatenate a different way, or use a different method to open/create the file?
All help/ideas are appreciated.

Answer 1

I do not really know what you're trying to achieve with the line
$objCalcTxt = ("C:\\xampp\\htdocs\\test.new\\upload\\$dynamicNameTxt");
if from what i understand it should just be a string:
$objCalcTxt = "C:\\xampp\\htdocs\\test.new\\upload\\".$dynamicNameTxt;
Also I'd suggest you provide the needed variables as arguments for the function insted of using globals
function sendCalc($objName, $ext, $dynamicNameTxt){
...
}

Answer 2

You are declaring the global variables inside your function. This could destroy their initial values.
Instead of using global variables in your function, rather pass the variables as arguments:
$objName = "dynamicName";
$ext = ".txt"
$dynamicNameTxt = $objName.$ext;
function sendCalc(objName, $ext, $dynamicNameTxt)
{
$objCalcTxt = ("C:\\xampp\\htdocs\\test.new\\upload\\$dynamicNameTxt");
$fp = fopen($objCalcTxt, 'x');
fwrite($fp, "Test\n");
fclose($fp);
}
Your other option is to specifically call the global variable:
global $objName;
global $ext;
global $dynamicNameTxt;
$objName = "dynamicName";
$ext = ".txt"
$dynamicNameTxt = $objName.$ext;
function sendCalc()
{
$objCalcTxt = ("C:\\xampp\\htdocs\\test.new\\upload\\".$GLOBAL['dynamicNameTxt']);
$fp = fopen($objCalcTxt, 'x');
fwrite($fp, "Test\n");
fclose($fp);
}