computer science 1620 variables and memory. review examples: write a program that calculates and...
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Review Examples:write a program that calculates and displays
the average of the numbers 45, 69, and 106.
Write a program that calculates and displays the average of the numbers 45, 69, and 106.
#include <iostream> using namespace std;
int main() {
return 0;}
Write a program that calculates and displays the average of the numbers 45, 69, and 106.
#include <iostream> using namespace std;
int main() {
return 0;}
Write a program that calculates and displays the average of the numbers 45, 69, and 106.
#include <iostream> using namespace std;
int main() { cout << (45 + 69 + 106)/3 << endl;
return 0;}
Write a program that calculates and displays the average of the numbers 45, 69, and 106.
#include <iostream> using namespace std;
int main() { cout << (45 + 69 + 106)/3 << endl;
return 0;}
We receive an incorrect answer, due to integer division dropping the decimal part.
Write a program that calculates and displays the average of the numbers 45, 69, and 106.
#include <iostream> using namespace std;
int main() { cout << (45 + 69 + 106)/3.0 << endl;
return 0;}
Now this is ok, as the numeratorwill be promoted to a floating pointnumber.
Review Examples:suppose that I invest $25000 into a mutual
fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
Suppose that I invest $25000 into a mutual fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
#include <iostream> using namespace std;
int main() {
return 0;}
Suppose that I invest $25000 into a mutual fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
#include <iostream> using namespace std;
int main() {
return 0;}
After one year, the fund will be worth 1.08 times what it was initially
After two years, the fund will be worth 1.08 times what it was after one year
After three years, the fund will be worth 1.08 times what it was after two year
Suppose that I invest $25000 into a mutual fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
#include <iostream> using namespace std;
int main() {
cout << "Year 1: $" << 25000 * 1.08 << endl; cout << "Year 2: $" << 25000 * 1.08 * 1.08 << endl; cout << "Year 3: $" << 25000 * 1.08 * 1.08 * 1.08 << endl;
return 0;}
The previous program works fine, but what do you notice?
#include <iostream> using namespace std;
int main() {
cout << "Year 1: $" << 25000 * 1.08 << endl; cout << "Year 2: $" << 25000 * 1.08 * 1.08 << endl; cout << "Year 3: $" << 25000 * 1.08 * 1.08 * 1.08 << endl;
return 0;} Repeat Calculations
Variablesa memory location that holds a valueAdvantages:
allow us to avoid repeated computation store a result, rather than recompute it
allow us to read user input coming soon!!
to understand C++ variables requires a little knowledge on how memory works
Program Memory - a Simplified Viewwhen you run a program
your operating system (Windows, Linux, MacOS) allocates a spot in memory for the program to run
a certain portion of memory holds the instructions
the machine instructions to be executed by the processor
the remaining portion is dedicated to storing data
Variables
Program Memory
your program's memory is a sequence of contiguous blocks
each block has an address it is in this memory that
you can store data
1000
1004
1008
1012
1016
1020
1024
1028
1032
1036
Variablea variable is named memory storage
that is, a variable is a location in memory that can be referenced by name
a variable allows the programmer access to a memory location, to store and retrieve data
Variables – Declaration to store a value using a variable, you must
first declare the variablevariable declarations take the following
syntax:
type name
type refers to the type of the value to be stored (such as int, double). It defines how much memory the variable is given.
name is the name of the variable. This is how you will refer to this value from now on.
#include <iostream> using namespace std;
int main() {
int amount;
return 0;
}
Example:
amount is the name of the variable. From this point forward, when the program sees the word amount, it knows you are referring to the value stored at that variable.
The variable's type is an int. This means that only integers can be stored in this variable. It also means that this variable will get 4 bytes of memory.
#include <iostream> using namespace std;
int main() {
double amount;
return 0;
}
Example 2:
The variable's type is an double. It means that this variable will get 8 bytes of memory.
#include <iostream>#include <string> using namespace std;
int main() {
string name;
return 0;
}
Example 2:
The variable's type is an string. The amount of memory it gets will vary with the size of the stored string.
We will have much to say aboutthe string type later on (when we talk about arrays). For now, just treat it like the other data types.
To use the string type, you must add this include statement.
Behind the scenes – Variable Declaration
#include <iostream> using namespace std;
int main() { int amount;
return 0;
}
Program Memory:
when a variable is declared, C++ reserves a spot in memory for that variable.
amount
Variable Namesnot just any name for a variable is permittedmust be a valid identifier rules:
the first character must be a letter or underscoreonly letters, digits, and underscore may followyou must not use a keyword
a word already used in C++ (like int)
some compilers have limits on identifier length
Variable Names what is a valid name, and what is invalid?
kev a1234 1234a _1234
cs1620a single double lethbridge
007bond main _ return
kev a1234 1234a lethbridge
cs1620a _1234 single double
007bond main _ return
john a1234 1234a lethbridge
cs1620a _1234 single double
007bond main _ return
Assignmentvariable declarations reserve the memoryassignment allows us to store a value in
memoryuses the = operatorsyntax:
the value of the expression is placed in memory
variable name expression=
Assignment
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
return 0;
}
Program Memory:
Assignment
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
return 0;
}
Program Memory:
when a variable is declared, C++ reserves a spot in memory for that variable.
int amount;
amount
Assignment
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
return 0;
}
10
Program Memory:
when a variable is assigned, the value of the expression is placed in memory
amount = 10;
amount
Note that the right hand side takes an expression
#include <iostream> using namespace std;
int main() { int amount; amount = 15 + 14;
return 0;}
29
Program Memory:
amounthence, you can include something other than a literalfor now, assume that the type of the variable and the type of the value should be the same
Assignment also applies to doubles and strings as well
#include <iostream> using namespace std;
int main() { double product; product = 15.0 * 14.0;
string name; name = “Letitia"; return 0;}
Retrievalvariable declarations reserve the memoryassignment allows us to store a value in
memoryhow do we retrieve the value?
the variable name itself can be used as an expression
when a variable is used as an expression, the value of that expression is whatever is being stored at that variable
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
cout << amount << endl;
return 0;
}
Program Memory:Program:
Output:
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
cout << amount << endl;
return 0;
}
Program Memory:Program:
Output:
int amount;
amount
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
cout << amount << endl;
return 0;
}
10
Program Memory:Program:
Output:
amount = 10;
amount
#include <iostream> using namespace std;
int main() { int amount;
amount = 10;
cout << amount << endl;
return 0;
}
10
Program Memory:Program:
Output:
cout << amount << endl;
amount
10
amount in this case is an expression
the value of that expression is the value stored in amount's memory
Where else can a variable be used as an expression?anywhere an expression is allowed
in an arithmetic expression
in an assignment statement
double amount;amount = 10.0;cout << amount + 24.0 << endl;
string name;name = ”Portia";string name2;name2 = name;
Note: Assignment is an operator has lower precedence than arithmetic operator hence, variable can be used in its own assignment
int amount;amount = 10;amount = amount + 20;
Arithmetic Expression evaluated firstAssignment evaluated after.
Another Note:variable declaration and assignment can be
combined into one statement
can also be written:
int amount;amount = 10;
int amount = 10;
Returning to our previous example:calculate the yearly balance on an
investment making 8% interest per yearcan we improve our original solution with a
variable?
Suppose that I invest $25000 into a mutual fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
#include <iostream> using namespace std;
int main() { cout << "Year 1: $" << 25000 * 1.08 << endl; cout << "Year 2: $" << 25000 * 1.08 * 1.08 << endl; cout << "Year 3: $" << 25000 * 1.08 * 1.08 * 1.08 << endl;
return 0;
}
Suppose that I invest $25000 into a mutual fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
#include <iostream> using namespace std;
int main() {
}
Suppose that I invest $25000 into a mutual fund that returns 8% per year. Write a program to calculate how much the fund will be worth after a) one year, b) two years c) three years
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl;
balance = balance * 1.08; cout << "Year 2: $" << balance << endl;
balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;
}
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
Program Memory:Program:
Output:
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
Program Memory:Program:
Output:
balance
double balance
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
25000.0
Program Memory:Program:
Output:
balance
balance = 25000.0
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
25000.0
Program Memory:Program:
Output:
balance
balance * 1.08;
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
27000.0
Program Memory:Program:
Output:
balance
balance = balance * 1.08;
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
27000.0
Program Memory:Program:
Output:
balance
cout << "Year 1: $" << balance << endl;
Year 1: $27000
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
27000.0
Program Memory:Program:
Output:
balance
Year 1: $27000
balance * 1.08;
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
29160.0
Program Memory:Program:
Output:
balance
Year 1: $27000
balance = balance * 1.08;
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
29160.0
Program Memory:Program:
Output:
balance
Year 1: $27000
cout << "Year 2: $" << balance << endl;
Year 2: $29160
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
29160.0
Program Memory:Program:
Output:
balance
Year 1: $27000Year 2: $29160
balance * 1.08;
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
31492.8
Program Memory:Program:
Output:
balance
Year 1: $27000Year 2: $29160
balance = balance * 1.08;
#include <iostream> using namespace std;
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl;
return 0;}
31492.8
Program Memory:Program:
Output:
balance
Year 1: $27000Year 2: $29160
cout << "Year 3: $" << balance << endl;
Year 3: $31492.8
Compare the two programs:
int main() {
double balance = 25000.0;
balance = balance * 1.08; cout << "Year 1: $" << balance << endl; balance = balance * 1.08; cout << "Year 2: $" << balance << endl; balance = balance * 1.08; cout << "Year 3: $" << balance << endl; return 0;}
int main() {
cout << "Year 1: $" << 25000 * 1.08 << endl; cout << "Year 2: $" << 25000 * 1.08 * 1.08 << endl; cout << "Year 3: $" << 25000 * 1.08 * 1.08 * 1.08 << endl; return 0;}
6 multiplications
3 multiplications
Assignment as Expressionassignment is a binary operator
similar to +, -, *, /, % right to left associative
assignment is actually an expression that is, the assignment statement has a value
the value of an assignment is: the value being placed in the variable's memory
int x;x = 10; This statement has a value.
Assignment as an Expression this means we can use assignment
wherever we use an expression1) In a cout statement
2) In an arithmetic expression
cout << (x = 10) << endl;
int y = (x=10) + 4;
These usesare quite uncommon
Assignment as an Expression3) In another assignment statement
this use is actually quite common that is, if you are setting two or more variables to
the same value, you can use one assignment as an expression for the other assignment
int x, y;x = y = 25;
int a,b,c,d,e,f;a = b = c = d = e = f = 0;
Assignment as an Expression3) In another assignment statement
The order in which assignment operator is evaluated: RIGHT to LEFT!
int x, y;x = y = 25;
25
Assignment as an Expressionnote the previous examples:
assignment has very low precedencesecond lowest (tied with others)when using assignment as an expression, you
should usually use parentheses
int y = (x=10) + 4;
cout << (x = 10) << endl;
Assignment as Expressionassignment is an example of an expression
that does more than simply represent a value
it (may) change the state of a variablesome other expressions have this effect as well
therefore, we require an updated definition:an expression is an entity in C++ that (1) always
has a value and (2) sometimes changes the state of the program
Write a program that converts 20 degrees Farenheit to Celsius.
#include <iostream> using namespace std;
int main() {
return 0;}
)32(9
5−= FC
Write a program that converts 20 degrees Farenheit to Celsius.
#include <iostream> using namespace std;
int main() {
double farenheit = 20.0;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
)32(9
5−= FC
What do you notice about the previous program?what happens if the temperature is 15
degrees? the program would have to be edited, then re-
compiled that is, all of our programs so far, once
compiled, produce exactly the same output
cin console input allows the user to enter data into your program this data can be stored and manipulated in the
same manner as the other data in your program Syntax:
cin >> variable
Notice that the direction of theredirect operator is opposite forthat of cout
The cin operator requires a variable. It is to this variablethat the inputted data is stored.
Write a program that converts any temperature farenheit to celsius.
#include <iostream> using namespace std;
int main() {
double farenheit = 20.0;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Write a program that converts any temperature farenheit to celsius.
#include <iostream> using namespace std;
int main() {
double farenheit = 20.0;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Write a program that converts any temperature farenheit to celsius.
#include <iostream> using namespace std;
int main() {
double farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Write a program that converts any temperature farenheit to celsius.
#include <iostream> using namespace std;
int main() {
double farenheit;
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
When you use the cin operator: the program simply stops and waits for
some data (and the enter key to be pressed)
it is usually a good idea to display instructions for the user to input some data (using cout)
otherwise, the impression may be that the program is not responding
this is known as prompting the user
Write a program that converts any temperature farenheit to celsius.
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Please enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Program Memory:Program:
Output:
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Program Memory:Program:
Output:
farenheit
double farenheit;
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Program Memory:Program:
Output:
farenheit
cout << "Enter a temperature in Farenheit:";
Enter a temperature in Farenheit:
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
Program Memory:Program:
Output:
farenheit
Enter a temperature in Farenheit: 20
cin >> farenheit;
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
20
Program Memory:Program:
Output:
farenheit
cin >> farenheit;
Enter a temperature in Farenheit: 20
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
20
Program Memory:Program:
Output:
farenheit
double celsius
Enter a temperature in Farenheit: 20
celsius
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
20
-6.66667
Program Memory:Program:
Output:
farenheit
double celsius = (5.0 / 9.0)*(farenheit – 32);
Enter a temperature in Farenheit: 20
celsius
#include <iostream> using namespace std;
int main() {
double farenheit;
cout << "Enter a temperature in Farenheit:";
cin >> farenheit;
double celsius = (5.0 / 9.0)*(farenheit – 32);
cout << farenheit << " F = " << celsius << " C" << endl;
return 0;}
20
-6.66667
Program Memory:Program:
Output:
farenheit
cout << farenheit << " F = " << celsius << " C" << endl;
Enter a temperature in Farenheit: 20
celsius
20 F = -6.66667 C
Multiple Inputs just as cout can accept multiple expressions
at once, cin can accept multiple variables at once:
Example:int left;
int right;
cin >> left >> right;
Notes about multiple inputs: the variables are filled from left to right
the input values are separated by whitespace
whitespace is ignored by cin (by default)
cin >> left >> right;
left receives the first value, right receives the second value.
Example: Write a program that accepts two numbers, and computes and displays their product:
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter two numbers:";
cin >> num1 >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
cin – Low level details the cin operator is an example of a data
streamwhen a user enters input, the input waits on
the data stream until the cin operator accepts it
this can sometimes produce some unexpected results
Example: Rewrite the multiplication program to only take one number at a time:
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
Program Memory:Program:
Output:
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
Program Memory:Program:
Output:
int num1;
num1
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
Program Memory:Program:
Output:
int num2;
num1
num2
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
Program Memory:Program:
Output:
cout << "Please enter a number:";
num1
num2
Please enter a number:
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
Program Memory:Program:
Output:
cin >> num1;
num1
num2
Please enter a number:
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
Program Memory:Program:
Output:
cin >> num1;
num1
num2
Please enter a number: 7 6
• The user has entered two numbers into the data stream.• cin only reads one of them.• the other number is still sitting on the data stream, waiting to be read.
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
7
Program Memory:Program:
Output:
cin >> num1;
num1
num2
Please enter a number: 7 6
• The user has entered two numbers into the data stream.• cin only reads one of them.• the other number is still sitting on the data stream, waiting to be read.
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
7
Program Memory:Program:
Output:
cout << "Please enter another number:";
num1
num2
Please enter a number: 7 6Please enter another number:
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
7
6
Program Memory:Program:
Output:
cin >> num2;
num1
num2
Please enter a number: 7 6Please enter another number:
• This cin statement retrieves the next number on the data stream, which is the 6 that was typed in previously.
#include <iostream> using namespace std;
int main() {
int num1; int num2;
cout << "Please enter a number:"; cin >> num1;
cout << "Please enter another number:"; cin >> num2;
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
return 0;}
7
6
Program Memory:Program:
Output:
cout << num1 << " * " << num2 << " = " << (num1 * num2) << endl;
num1
num2
Please enter a number: 7 6Please enter another number: 7 * 6 = 42