SIMPLE ARITHMETIC OPERATORS
An operator is a symbol that ‘’operates’’ on one or more expressions, producing a value that can be assigned to a variable. We have already encountered the output operator << and the assignment operator = .
Some of the simplest operators are the operators that do arithmetic: +, -, *, /, and %. These operate on integer types to produce another integer type: m + n produces the sum m plus n, m – n produces the difference m minus n, -n produces the negation of n, m*n produces the product m times n, m/n produces the integer quotient when m is divided by n, and m%n produces the integer remainder when m is divided by n. These six operators are summarized in the following table in the example below.
Table: Integer Arithmetic Operators
|
Operator |
Description |
Example |
|
+ |
Add |
m+n |
|
– |
Subtract |
m-n |
|
– |
Negate |
-n |
|
* |
Multiply |
m*n |
|
/ |
Divide |
m/n |
|
% |
Remainder |
m%n |
EXAMPLE: Integer Operators
This program use of the six arithmetic operators:
#include < iostream.h >
// Tests arithmetic operators :
main ()
{
int m = 38, n = 5;
cout << m << “ + “ << n << “ = “ << (m + n) << end1 ;
cout << m << “ – “ << n << “ = “ << (m – n) << end1 ;
cout << “ – “ << n << “ = “ << ( -n ) << end1 ;
cout << m << “ * “ << n << “ = “ << (m * n) << end1 ;
cout << m << “ / “ << n << “ = “ << (m / n) << end1 ;
cout << m << “ % “ << n << “ = “ << (m % n) << end1 ;
return 0 ;
}
OUTPUT:
38 + 5 = 43
38 – 5 = 33
** – 5 = -5
38 * 5 = 190
38 / 5 = 7
38 % 5 = 3
Note that 38 / 5 = 7 and 38%5 = 3. These two operations together provide complete information about the ordinary division of 38 by 5: 38 / 5 = 7.6. The resulting integer part is 35 / 5 = 7, and the fractional part is 3/5 = 0.6. The integer quotient 7 and the integer reminder 3 can be recombined with the dividend 38 and the divisor 5 in the following relation :
The integer quotient and remainder operators are more complicated if the integers are not positive. Of course, the divisor should never be zero. But if either m or n is negative, then m/n and m%n may give different results on machines. The only requirement is that
q*n + r == m
where q = m/n and r = m%n.
For example, -14 divided by 5 is -2.8. For the integer quotient, this could be rounded to -3 or to -2 . If your computer rounds, q to -2, then r will be -4.
EXAMPLE: Division with Negative Integer
This program is used to determine how the computer handles the division of negative integers:
#include < iostream.h >
// Tests quotient and remainder operators:
main ()
{
int m = -14, n = 5, q = m/n, r = m%n;
cout << “m = “ << m << end1 ;
cout << “n = “ << n << end1 ;
cout << “q = “ << q << end1 ;
cout << “r = “ << r << end1 ;
cout << “q*n + r = “ << “ ( “ << q << “) * ( “ << n << “ ) + “
<< r << “ = “ << q*n + r << “ = “ << M << end1;
Return 0;
}
OUTPUT:
m = -14
n = 5
q = -2
r = -4
q*n + r = (-2) * (5)= -14= -14
This shows the same results both form a UNIX workstation using a Motorola 68040 processor and from a DOS PC using an Intel Pentium processor.
Ref. By: JOHN R. HUBBARD, Ph.D. Professor of Mathematics and Computer Science, University of Richmond
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