A simple class in PHP to calculate the size of file

I have received B.Sc. degree in Computer Science and Engineering from Khulna University of Engineering and Technology, (KUET) Bangladesh in 2003 and Master of Business Administration in Management from University of Dhaka, Bangladesh in 2009. I started my IT career as a Software Engineer at BDCOM Online Limited, then worked for BRAC BDMail Network Limited (bracNet). At present, I am working with Application Development, Integration and Maintenance department of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) - an international health research organization located in Dhaka, Bangladesh, dedicated to saving lives through research and treatment.