Create a unique name for the uploaded image - php

Question

I have a certain code for image upload .I found this on the internet and there was no explanation of the code either.What i can understand from the code is that php upload a certain file makes it a temporary file and then moves the temporary file to the original location
Code Looks something like this
$filename = $_FILES["img"]["tmp_name"];
list($width, $height) = getimagesize( $filename );
move_uploaded_file($filename, $imagePath . $_FILES["img"]["name"]);
What happens now is that when i try to provide an unique name to the image when it is being moved using the move_uploaded_file then a file does come up inside the folder but it says an invalid file and with the extension type of file.
My code for trying to achieve the same but with an unique name/id for the uploaded image.
$uniquesavename=time().uniqid(rand());
$filename = $_FILES["img"]["tmp_name"];
list($width, $height) = getimagesize( $filename );
move_uploaded_file($filename, $imagePath . $uniquesavename);
How to achieve the same as before and could you please explain me the previous code as well?

Answer 1

Sample code:
// Get file path from post data by using $_FILES
$filename = $_FILES["img"]["tmp_name"];
// Make sure that it's a valid image which can get width and height
list($width, $height) = getimagesize( $filename );
// Call php function move_uploaded_file to move uploaded file
move_uploaded_file($filename, $imagePath . $_FILES["img"]["name"]);
Please try this one:
// Make sure this imagePath is end with slash
$imagePath = '/root/path/to/image/folder/';
$uniquesavename=time().uniqid(rand());
$destFile = $imagePath . $uniquesavename . '.jpg';
$filename = $_FILES["img"]["tmp_name"];
list($width, $height) = getimagesize( $filename );
move_uploaded_file($filename, $destFile);
Edit 1:
To get image type in two ways:
Get the file type from upload file name.
Use php function as below
CODE
// Get details of image
list($width, $height, $typeCode) = getimagesize($filename);
$imageType = ($typeCode == 1 ? "gif" : ($typeCode == 2 ? "jpeg" : ($typeCode == 3 ? "png" : FALSE)));

Answer 2

$name = $_FILES['file']['name'];
$tmp_name = $_FILES['file']['tmp_name'];
$location = "uploads/";
$new_name = $location.time()."-".rand(1000, 9999)."-".$name;
if (move_uploaded_file($tmp_name, $new_name)){
echo "uploaded";
}
else{
sleep(rand(1,5));
$new_name = $location.time()."-".rand(1000, 9999)."-".$name;
if (move_uploaded_file($tmp_name, $new_name)){
echo "uploaded";
}
else{
echo"failed, better luck next time";
}
}
here, location is folder inside directory, i mainly create folder "uploads"
time() adds timestamp , which is always unique, until two person upload at same time, which is rare.
moreover, adding 4 digit random number to it , making combination rarest
after that adding actual file name , to making combination unique.
why i use it :
u can extract timestamp later if u need to know when image was uploaded.
u can extract actual filename too.
Lets, say our so unique combination somehow fails,
then, php instance will wait for 1 to 5 second whatever random number is generated. and rename with latest timestamp and regenerated random number.
It's the best u can think of without being resource hog.

Answer 3

you can use
$strtotime = strtotime("now");
$filename = $strtotime.'_'.$_FILES['file']['name'];