Getting started with C [4]

Now that you know how C language works,I will show you how to create a function, I will tell you how to work with functions, and why are functions so important in any programming language. I will start with a very simple example, I will gather two numbers using a function.

#include "stdafx.h"
#include <stdio.h>


int amount(int, int);

int main()
{
	int a = 0,b =0;

	printf("a:");
	scanf("%d", &a);

	printf("b:");
	scanf("%d", &b);

	printf("%d + %d = %d",a,b,amount(a,b));

	getchar();

    return 0;
}

int amount(int a, int b)
{
	int c;
	c = a + b;

	return c;
}

This was a very simple example, now let’s try to do something more fun and more complex.

#include "stdafx.h"
#include <stdio.h>

int amount(int, int);
int subtract(int, int);
int multiplication(int,int);
int division(int,int);

void menu();

int main()
{
	int a;
	int b;
	printf("a:");
	scanf("%d", &a);

	printf("b:");
	scanf("%d", &b);

	menu();

	int option;

	do{
	    printf("\\nChoose Option:");
	    scanf("%d",&option);

		switch(option)
		{
		case 1:
			printf("a + b = %d", amount(a,b));
			break;

		case 2:
			printf("a - b = %d", subtract(a,b));
			break;

		case 3:
			printf("a * b = %d", multiplication(a,b));
			break;

		case 4:
			printf("a / b = %d", division(a,b));
			break;

		default:
			printf("Invalid Input");

		}
	}while(option != 5);

	getchar();

	return 0;
}

int amount(int a, int b)
{
	int c;
	c = a + b;

	return c;
}

int subtract(int a, int b)
{
	int c;
	c = a - b;

	return c;
}


int multiplication(int a, int b)
{
	int c;
	c = a * b;

	return c;
}

int division(int a, int b)
{
	int c;
	c = a / b;

	return c;
}

void menu()
{
	printf("**********************");
	printf("\\n1. +");
	printf("\\n2. -");
	printf("\\n3. *");
	printf("\\n4. /");
	printf("\\n**********************");
}

Well, is not so complex after all, but is a very good example of how functions works. I don’t know what to tell you more, but if you have any kind of questions don’t hesitate to ask me. I will answer, and I will try to help you as much as I can. Working with functions is very important and you need to understand this very well in order to progress with any programing language.
I made you another very simple and short example, look at this code:

#include "stdafx.h"
#include <stdio.h>

int max2(int, int);
int max3(int, int, int);

int main()
{
    int a,b,c;
    printf("a=");
    scanf("%d", &a);
    printf("b=");
    scanf("%d", &b);
    printf("c=");
    scanf("%d", &c);

    printf("\\nMax2(%d,%d) = %d", a,b, max2(a,b));
    printf("\\nMax3(%d,%d,%d) = %d", a,b,c, max3(a,b,c));

	getchar();
	getchar();

    return 0;
}

int max2(int a, int b)
{
    return a > b ? a:b;
}

int max3(int a, int b, int c)
{
    int m = max2(a,b);
    m = max2(m,c);
    return m;
}

Maybe you don’t understand this line:

 return a > b ? a:b;

This means: If a > b return a else return b

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