1
CS 112 Introduction to
Programming
Lecture #6:
Arithmetic
and Assignment Operations
http://flint.cs.yale.edu/cs112/
2
Outline
qAdmin. and review
ØArithmetic operations
qAssignment operations
3
Arithmetic Expressions
rAn expression is a combination of operators and
operands
rArithmetic expressions (we will see logical
expressions later) compute numeric results and make
use of the arithmetic operators:
Addition +
Subtraction -
Multiplication *
Division /
Remainder %
rThere are no exponents
Outline
Arithmetic.cs
1 // Arithmetic.cs
2 // An arithmetic program.
3
4 using System;
5
6class Arithmetic
7 {
8 static void Main( string[] args )
9 {
10 string firstNumber, // first string entered by user
11 secondNumber; // second string entered by user
12
13 int number1, // first number to add
14 number2; // second number to add
15
16 // prompt for and read first number from user as string
17 Console.Write( "Please enter the first integer: " );
18 firstNumber = Console.ReadLine();
19
20 // read second number from user as string
21 Console.Write( "\nPlease enter the second integer: " );
22 secondNumber = Console.ReadLine();
23
24 // convert numbers from type string to type int
25 number1 = Int32.Parse( firstNumber );
26 number2 = Int32.Parse( secondNumber );
27
28 // do operations
29 int sum = number1 + number2;
30 int diff = number1 -number2;
31 int mul = number1 * number2;
32 int div = number1 / number2;
33 int mod = number1 % number2;
This is the start of class Arithmetic
Two string variables
defined over two lines
The comment after the
declaration is used to briefly
state the variable purpose
These are two ints that are declared
over several lines and only use one
semicolon. Each is separated by a coma.
Console.ReadLine is used to take the
users input and place it into a variable.
This line is considered a prompt
because it asks the user to input data.
Int32.Parse is used to convert
the given string into an integer.
It is then stored in a variable.
The operation result are stored
in result variables.
Outline
Arithmetic.cs
32 // display results
33 Console.WriteLine( "\n{0} + {1} = {2}.", number1, number2, sum );
34 Console.WriteLine( "\n{0} –{1} = {2}.", number1, number2, diff );
35 Console.WriteLine( "\n{0} * {1} = {2}.", number1, number2, mul );
36 Console.WriteLine( "\n{0} / {2} = {2}.", number1, number2, div );
37 Console.WriteLine( "\n{0} % {1} = {2}.", number1, number2, mod );
34
35 } // end method Main
36
37 } // end class Arithmetic
Putting a variable out through Console.WriteLine
is done by placing the variable after the text while
using a marked place to show where the variable
should be placed.
6
Division and Remainder
rIf both operands to the division operator (/) are integers, the
result is an integer (the fractional part is discarded)
rThe remainder operator (%) returns the remainder after dividing the
second operand into the first
8 / 12 equals?
14 / 3 equals? 4
0
14 % 3 equals?
8 % 12 equals?
2
8
