How to make image name with post_id wordpress

Question

I have a project to auto make images with each post id so i have to save each separated image associated with each post and the image name should be post id i tried these methods but not succeed

wp-content/uploads/2014/<?php the_ID(); ?>.png

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$id = get_the_ID();

then

file_put_contents('wp-content/uploads/2014/text-$id.png', $image);

so i need a php method to save image with post id in ths line

file_put_contents('wp-content/uploads/2014/IMAGENAMEPOSTIDHERE.png', $image);

THANKS

Answer 1

If $image is already fine, then just simple use concatenation or use double quotes to use that ID:

file_put_contents('wp-content/uploads/2014/text-$id.png', $image);
// you're using single quotes, variables will not be interpolated

Either:

$id = get_the_ID();
file_put_contents('wp-content/uploads/2014/text-'.$id.'.png', $image);

or

file_put_contents("wp-content/uploads/2014/text-$id.png", $image);

_{Note: Assuming you have proper permissions.}