In C how do I calculate the size of a file?

The first part of the lab is to write a program to read the complete contents of a file to a string. This code will be used in subsequent coding problems. You will need 3 functions: main(), read_file() and write_file(). The main function contains the driver code. The read_file() function reads the complete contents of a file to a string. The write_file( writes the complete contents of a string to a file. The read_file( will require: Open the file for reading Calculating the size of a file Allocating memory to read the file to a string Rewinding the file to the beginning Reading the files contents to the allocated string Close the file