Read a file called populations.txt and populate a php associative array with the values read from the file.

Here is an example populations.txt file:

Dhaka, 23 million

Bangaluru, 21 million

New York, 9 million

Emporia, 23 thousand

Here's some pseudo code:

open the file

loop through the lines in the file

read a line into a string variable

explode (or is it split, or something else) the string into key value pairs

save the key value pair into your associative array

print a table header

loop through the keys of your associative array

print each key value pair

Then move the file and write to another file and read that file in the reverse order Using sprintf

like this

23 million, Dhaka

21 million, Bangaluru

9 million , New York

Using sprintf