Hi, I am running a wamp server in windows. I am trying to compile C file which I upload and then I will try to download it. I can do an upload of c file. I also can compile if I specify the name of the c file as the source and the name of the output that I want in the code. I also can download it. However, I am currently stuck at compile. The code below is working $output = system('"C:\Program Files\CodeBlocks\MinGW\bin\gcc.exe" "C:\Program Files\EasyPHP-5.3.9\www\upload\test1.c" -O3 -o "C:\Program Files\EasyPHP-5.3.9\www\upload\test1.exe"'); PHP: I want the file that I upload is the file that I can compile Hence I modify it to $source=dirname(__FILE__).'\upload\\'.$_FILES['uploadedfile']['name']; echo $source; //mainfilename=test1 $outputname=substr_replace($_FILES['uploadedfile']['name'], 'exe', strpos($_FILES['uploadedfile']['name'], '.')+1); $destination=dirname(__FILE__).'\upload\\'.$outputname;echo $destination; $output = system('"C:\Program Files\CodeBlocks\MinGW\bin\gcc.exe" $source -O3 -o $destination'); PHP: $source and $destination produce the exact string as the code which is working. What am I missing to make this work?