Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

Chapter 3 ■ Programs with Sequence Logic
}
sum = a + b;
printf("%d + %d = %d\n", a, b, sum);
C allows us to declare a variable and give it an initial value in one statement so we could write
the program more concisely (without the comment) as Program P3.1:
Program P3.1
#include <stdio.h>
int main() {
int a = 14;
int b = 25;
int sum = a + b;
printf("%d + %d = %d\n", a, b, sum);
}
And since, as discussed earlier, we do not really need the variable sum, this program can be
written as Program P3.2.
Program P3.2
#include <stdio.h>
int main() {
int a = 14;
int b = 25;
printf("%d + %d = %d\n", a, b, a + b);
}
This program is very restrictive. If we wish to add two other numbers, we will have to change
the numbers 14 and 25 in the program to the ones required. We would then have to re-compile
the program. And each time we want to add two different numbers, we would have to change the
program. This can become very tedious.
It would be nice if we could write the program in such a way that when we run the program,
we will have the opportunity to tell the program which numbers we wish to add. In this way, the
numbers would not be tied to the program, and the program would be more flexible. When we
“tell” the program the numbers, we say we are supplying data to the program. But how do we get
the program to “ask” us for the numbers and how do we “tell” the program what the numbers are?
We can get the program to prompt us for a number by printing a message such as:
Enter first number:
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