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

Chapter 3 ■ Programs with Sequence Logic
using a printf statement. The program must then wait for us to type the number and, when it is
typed, read it. This can be done with the scanf statement. (Strictly speaking, printf and scanf
are functions, but the distinction is not too important for us.) Before we look at this statement, let
us rewrite the algorithm using these new ideas:
prompt for the first number
read the number
prompt for the second number
read the number
find the sum
print the sum
We can implement this algorithm in C as Program P3.3.
Program P3.3
//prompt for two numbers and find their sum
#include <stdio.h>
int main() {
int a, b;
printf("Enter first number: ");
scanf("%d", &a);
printf("Enter second number: ");
scanf("%d", &b);
printf("%d + %d = %d\n", a, b, a + b);
}
When run, the first printf statement will print:
Enter first number:
The scanf statement, explained shortly, will cause the computer to wait for the user to type a
number.
Suppose she types 23; the screen will look like this:
Enter first number: 23
When she presses the “Enter” or “Return” key on the keyboard, scanf reads the number and
stores it in the variable a.
The next printf statement then prompts:
Enter second number:
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