(50 pts) Write a program that asks user an arithmetic operator('+','','' or '/') and two operands and perform the corresponding calculation on the operands. Specific requirements: (1) Your main function accepts inputs and display calculation result.

(2) Write four functions to perform the four calculations. Call these functions in your main function.

(3) Repeatedly asks for inputs, calculate and display result until user input nonnumeric value for operands.

Hint: you can put getchar() right after scanf() to get rid of the newline character that comes though input to scanf(), so it wont affect the following single character input either by scanf() or getchar().