The first example only printed text to the screen, which is an output device. This example reads two numbers from the keyboard, adds them and prints the result.
#include <stdio.h>
#include <conio.h>
int main()
{
int number1, number2, total;
printf("Enter the first number: ");
scanf("%d", &number1);
printf("Enter the other number: ");
scanf("%d", &number2);
total = number1 + number2;
printf("Total: %d", total);
getch();
return 0;
}
The `int` expression on the first line specifies the data type; the comma-separated expressions that follow are variables.
Variables must first be declared. Three integer variables are declared here.
The `printf()` function prints “Enter the first number:” on the screen.
As shown in `scanf("%d", &number1);`, the function receives two parameters, although it can receive more.
The first parameter (`%d`) indicates that the input is a decimal integer.
Notice the ampersand (`&`) before the second parameter. In this context, the operator refers to an address.
In brief, `&number1` passes the address of `number1` to the function.