Structured programming is a problem-solving strategy and a methodology that includes two guidelines: the flow of control in a program should be as simple as possible, and the construction of a program...

Extracted text: Structured programming is a problem-solving strategy and a methodology that includes two guidelines: the flow of control in a program should be as simple as possible, and the construction of a program should embody top-down design. The top-down design, also referred to as stepwise refinement, consists of repeatedly decomposing a problem into smaller problems. Eventually, one has a collection of small problems or tasks, each of which can be easily coded. The function construct in C is used to write code that solves the small problems that results from this decomposition. These functions are combined into other functions and ultimately used in main(..) to solve the original problem. The function mechanism is provided in C to perform distinct programming tasks. Some functions, such as printf(..) and scanf(..), are provided by the system; some others can be written by the programmer. Write a C program that includes the definitions of the following functions: a) is_lower(..) : is it a lower-case letter b) is_upper(..) : is it an upper-case letter c) is_alpha(..) : is it an alphabet d) is_digit(..) : is it a digit e) is_alphanum(..) : is it an alphanumeric symbol f) to_lower(..) : converts to a lower-case letter if it is upper g) to_upper(..) : converts to an upper-case letter if it is lower h) distance(..) : calculates the distance between two discrete points in a Cartesian coordinate system as below d = U2 – yı)² + (x2 – x1)² i) is_prime(..) : finds out whether the number is prime or not