C code review shows entered two years difference days

This C code shows how shows entered two years difference days. And code is helpful while user is in between date manipulation task.

C code review converts user input into upper or lower case string

This C code shows how to convert user input into upper/lower case string. And code is helpful in string manipulation task.

C code review takes integer and shows its binary form

This C code shows how to convert integer input into binary and shows it to user. And code is helpful in boolearn algebra.

C code review: calculates perimeter, area & volume of rectangle

This C code shows how to calculates perimeter, area & volume of rectangle, using language supplied operators. And uses if else constructors to prepare menu.