The method and steps of realizing Calculator function by using function pointer Array in C language

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Let's review the concept first:

Pointer array-the array where pointers are stored

Function pointer-A pointer that stores the address of a function

Array of function pointers-an array of function pointers

Next, let's talk about the functions of the calculator to be made this time:

1.add-addition

2.sub-subtraction

3.mul-multiplication

4.div-division

0.exit-exit

Specifically, it is explained through the code:

(1) first write a menu program, and print the menu first when running the program.

Void menu () {printf ("*\ n"); printf ("* 1.add *\ n"); printf ("* 2.sub *\ n"); printf ("* 3.mul *\ n") Printf ("* 4.div *\ n"); printf ("* 0.exit *\ n"); printf ("*\ n");}

(2) write four functions about addition, subtraction, multiplication and division.

Int Add (int x, int y) {return x + y;} int Sub (int x, int y) {return x-y;} int Mul (int x, int y) {return x * y;} int Div (int x, int y) {return x / y;}

(3) write the main function, define input as the number you want to enter to select the function; define x and y as the operands you want to enter; and then call the menu function menu () in the main program.

Int main () {int x = 0; int y = 0; int input = 0; menu ();}

(4) use the do while loop, and the if else statement to establish the rules, exit the loop if the input input is 0, while (input) represents a non-zero input will continue the cycle; if the input between 1 and 4 corresponds to the calculator menu function, then you need to enter two numbers; if beyond this range then re-cycle.

Int main () {int x = 0; int y = 0; int input = 0; menu (); do {printf ("Please select what you want to do:\ n"); scanf ("% d", & input); if (input = = 0) {printf ("quit calculator!\ n");} else if (input > = 1 & input = 1 & input