I need to make a method to generate and download a txt file where the string length is fixed and reserved. For example, I need to insert data from a record containing id, name, NIF. The id can be 100, therefore, I must reserve three spaces for that string, so if I write the id 1 should be the 2 characters blank, and then the "name" should be followed, without line break. My idea is use a for() loop and when file position is [i], insert the array element [i]. My question is how to define size of that position in the file?
Are you looking for str_pad? http://php.net/manual/en/function.str-pad.php
str_pad(1, 3, ' ', STR_PAD_LEFT) will " 1". You could have an array telling how long each string should be and use $lenghts[$i] inside your loop to set the padding size