Formatting Output

By default, consecutive integer, floating-point, and string values are output with no spaces between them.

Manipulators are used to control the horizontal spacing of the output. (endl is one we’ve already seen)

Manipulators we’ll use now

endl first three defined in iostream

fixed

showpoint

setw last two defined in iomanip

setprecision

setw

setw (set width) lets us control how many character positions the next data item should occupy when it is output. (used for numbers and strings, not chars).

The argument to setw is an integer fieldwidth specification, the data item is right-justified within the fieldwidth.

If you don’t specify enough characters, the minimum number of characters is used anyway.

setw Examples

Statement (ans = 33, num = 7132) Output ( means blank)

cout << setw(4) << ans 33

setw Examples

Statement   (ans = 33, num = 7132)   Output ( means blank))

cout << setw(4) << ans << setw(5)      337132

        << num

setw Examples

Statement (ans = 33, num = 7132) Output ( means blank) cout << setw(4) << ans << setw(5) 337132Hi

<< num << setw(4) << “Hi”;

setw Examples

Statement   (ans = 33, num = 7132)   Output ( means blank) cout << setw(4) << ans << setw(5)      337132Hi

        << num << setw(4) << “Hi”;

cout << setw(2) << ans        33

setw Examples

Statement   (ans = 33, num = 7132)   Output ( means blank) cout << setw(4) << ans << setw(5)      337132Hi

        << num << setw(4) << “Hi”;

cout << setw(2) << ans << setw(4)     337132

     << num

setw Examples

Statement   (ans = 33, num = 7132)   Output ( means blank) cout << setw(4) << ans << setw(5)      337132Hi

        << num << setw(4) << “Hi”;

cout << setw(2) << ans << setw(4)     337132Hi

     << num << setw(2) << “Hi”;

cout << setw(6) << ans << setw(3)     33Hi7132

     << num << setw(5) << “Hi”;

cout << setw(7) << “Hi” << setw(4)     Hi7132

     << num;

cout << setw(1) << ans 33

setw Examples

Statement   (ans = 33, num = 7132)   Output ( means blank)

cout << setw(4) << ans << setw(5)     337132Hi

        << num << setw(4) << “Hi”;

cout << setw(2) << ans << setw(4)     337132Hi

     << num << setw(2) << “Hi”;

cout << setw(6) << ans << setw(3)     33Hi7132

     << num << setw(5) << “Hi”;

cout << setw(7) << “Hi” << setw(4)     Hi7132

     << num;

cout << setw(1) << ans << setw(5)     337132

     << num;

cout << “Hi” << setw(5) << ans     Hi337132

     << num;

Manipulating
Floating-Point Numbers

setw also works with floating-point numbers (remember that a decimal point is a character)

If you don’t want numbers to appear in scientific notation, use fixed.

If you want whole numbers printed with a .0 appended, use showpoint.

If you want to control the number of decimal places that are displayed, use setprecision(n), where n is the number of decimal places desired. Unlike setw, setprecision stays in effect until you explicitly change it.

Floating-Point
Output Examples

Value

of x Statement Output ( means blank)

cout << fixed;

310.0 cout << setw(10)

<< setprecision(2) << x; 310.00

Floating-Point
Output Examples

Value

of x Statement Output ( means blank) cout << fixed;

310.0 cout << setw(10)

<< setprecision(2) << x; 310.00

310.00 cout << setw(10)

<< setprecision(5) << x; 310.00000

310.0 cout << setw(7)

<< setprecision(5) << x; 310.00000

Bad Style Example

//****************************************************************

// HouseCost program

// This program computes the cost per square foot of

// living space for a house, given the dimensions of

// the house, the number of stories, the size of the

// nonliving space, and the total cost less land

//****************************************************************

#include <iostream>

#include <iomanip>// For setw() and setprecision()

using namespace

std;

const float WIDTH = 30.0; // Width of the house

const float LENGTH = 40.0; // Length of the house

const float STORIES = 2.5; // Number of full stories

const float NON_LIVING_SPACE = 825.0; // Garage, closets, etc.

Bad Style
Example Continued

const float PRICE = 150000.0; // Selling price less land

int main(){ float grossFootage; // Total square footage

    float livingFootage;        // Living area

float costPerFoot; // Cost/foot of living area

    cout << fixed << showpoint; // Set up floating pt.

//   output format

grossFootage = LENGTH * WIDTH * STORIES;livingFootage =

grossFootage - NON_LIVING_SPACE; costPerFoot = PRICE /

livingFootage; cout << "Cost per square foot is “

<< setw(6) << setprecision(2) << costPerFoot << endl;

return 0;

}

Good Style Example

//****************************************************************

// HouseCost program

// This program computes the cost per square foot of

// living space for a house, given the dimensions of

// the house, the number of stories, the size of the

// nonliving space, and the total cost less land

//****************************************************************

#include <iostream>

#include <iomanip>    // For setw() and setprecision()

using namespace std;

const float WIDTH = 30.0;               // Width of the house

const float LENGTH = 40.0;              // Length of the house

const float STORIES = 2.5;              // Number of full stories

const float NON_LIVING_SPACE = 825.0;   // Garage, closets, etc.

const float PRICE = 150000.0;           // Selling price less land

Good Style
Example Continued

int main()

{

    float grossFootage;         // Total square footage

    float livingFootage;        // Living area

    float costPerFoot;          // Cost/foot of living area

    cout << fixed << showpoint; // Set up floating pt.

                                 //   output format

    grossFootage = LENGTH * WIDTH * STORIES;

    livingFootage = grossFootage - NON_LIVING_SPACE;

    costPerFoot = PRICE / livingFootage;

    cout << "Cost per square foot is "

         << setw(6) << setprecision(2) << costPerFoot << endl;

    return 0;

}

Additional string Operations

Now, we consider four functions that operate on strings: length, size, find, substr

The length and size functions both return an unsigned integer value equal to the number of characters in the string.

The find function searches a string to find the first occurrence of a particular substring and returns an unsigned integer. If the substring is found, it returns the position where the match begins, if not found, it returns a special number.

The substr function returns a particular substring of a string.

The length and size functions

If myName is a string variable, a call to length looks like this:

myName.length()

The length function requires no arguments, but you must still use parentheses.

Also, length is value-returning, so the call must appear in an expression.

Example Using
length and size

Example:

string firstName;

string fullName;

firstName = “Alexandra”;

cout << firstName.length() << endl; // Prints 9

fullName = firstName + “ Jones”;

cout << fullName.length() << endl; // Prints 15

More About string

string is a C++ class, which has data types and functions associated with it.

Other classes may have a length function. To get the length function associated with string, we use the dot operator with a string variable.

string has a data type associated with it to store a string length, string::size_type. Another class could also have size_type.

string::size_type specifies the size_type associated with string.

More About string

Example

string firstName;

string::size_type len;

firstName = “Alexandra”;

len = firstName.length();

The find Function

Example Usage

string str1, str2;

str1.find(“the”)

str1.find(str2)

str1.find(str2 + “abc”)

If the string is not found, a special value (string::npos) is returned. The return value type is string::size_type.

Examples Using find

        0123456789012345678901234567890

str1 = “Programming and Problem Solving”;

str2 = “gram”;

Function Call Value Returned by Function

str1.find(“and”)          12

str1.find(“Programming”)           0

str2.find(“and”) string::npos

str1.find(“Pro”)           0

Examples Using find

        0123456789012345678901234567890

str1 = “Programming and Problem Solving”;

str2 = “gram”;

Function Call               Value Returned by Function

str1.find(“and”)          12

str1.find(“Programming”)           0

str2.find(“and”) string::npos

str1.find(“Pro”)           0

str1.find(“ro” + str2)           1

str1.find(“Pr” + str2) string::npos

The substr Function

Sample function call:

myString.substr(5, 20)

Substr returns a string, the arguments to it are of type string::size_type.

Examples Using substr

0123456789012345678901234567890

myString = “Programming and Problem Solving”;

Function Call String Returned by Function

myString.substr(0, 7) “Program”

Examples Using substr

            0123456789012345678901234567890

myString = “Programming and Problem Solving”;

Function Call String Returned by Function

myString.substr(0, 7)                 “Program”

myString.substr(7, 8)                “ming and”

Examples Using substr

            0123456789012345678901234567890

myString = “Programming and Problem Solving”;

Function Call String Returned by Function

myString.substr(0, 7)       “Program”

myString.substr(7, 8)       “ming and”

myString.substr(10, 0            “”

myString.substr(24, 40)       “Solving”

myString.substr(40, 24)         Error

StringOps Program

//****************************************************************

// This program demonstrates several string operations

//****************************************************************

#include <iostream>

#include <string>     // For string type

using namespace std;

int main()

{

    string fullName;

    string name;

    string::size_type startPos;

    fullName = "Jonathan Alexander Peterson";

    startPos = fullName.find("Peterson");

    name = "Mr. " + fullName.substr(startPos, 8);

    cout << name << endl;

    return 0;

}

Problem-Solving Case Study

Problem: You are asked to calculate the total cost of painting traffic cones in three different colors. The cone company uses the area painted to estimate the total cost.

Output: The surface area of the cone in square feet, and the costs of painting the cone in the three different colors, all displayed in floating point form to three decimal places.

Discussion: Cones are measured in inches. A typical cone is 30 inches high and 8 inches in diameter. Red, blue, and green paint cost 10, 15, and 18 cents per square foot, respectively. The non-base surface area of a cone is pr(r² + h²)^1/2, where r is the radius of the cone and h is its height.

High-Level Algorithm

ConePaint Program

//****************************************************************

// This program computes the cost of painting traffic cones in

// each of three different colors, given the height and diameter

// of a cone in inches, and the cost per square foot of each of

// the paints

//****************************************************************

#include <iostream>

#include <iomanip>    // For setw() and setprecision()

#include <cmath>      // For sqrt()

using namespace std;

const float HT_IN_INCHES = 30.0;    // Height of a typical cone

const float DIAM_IN_INCHES = 8.0;   // Diameter of base of cone

const float INCHES_PER_FT = 12.0;   // Inches in 1 foot

More ConePaint Program

const float RED_PRICE = 0.10;       // Price per square foot

                                    //   of red paint

const float BLUE_PRICE = 0.15;      // Price per square foot

                                    //   of blue paint

const float GREEN_PRICE = 0.18;     // Price per square foot

                                    //   of green paint

const float PI = 3.14159265;        // Ratio of circumference

                                    //   to diameter

int main()

{

    float heightInFt;               // Height of the cone in feet

    float diamInFt;                 // Diameter of the cone in feet

    float radius;                   // Radius of the cone in feet

    float surfaceArea;              // Surface area in square feet

Yet More ConePaint

       float redCost;         // Cost to paint a cone red

    float blueCost;       // Cost to paint a cone blue

    float greenCost;      // Cost to paint a cone green

    cout << fixed << showpoint;      // Set up floating-pt.

                                     //   output format

    // Convert dimensions to feet

    heightInFt = HT_IN_INCHES / INCHES_PER_FT;

    diamInFt = DIAM_IN_INCHES / INCHES_PER_FT;

    radius = diamInFt / 2.0;

    // Compute surface area of the cone

    surfaceArea = PI * radius *

                  sqrt(radius*radius + heightInFt*heightInFt);

Cone Paint Program Concluded

       // Compute cost for each color

    redCost = surfaceArea * RED_PRICE;

    blueCost = surfaceArea * BLUE_PRICE;

    greenCost = surfaceArea * GREEN_PRICE;

    // Print results

    cout << setprecision(3);

    cout << "The surface area is " << surfaceArea << " sq. ft."

         << endl;

    cout << "The painting cost for" << endl << "   red is";

    cout << setw(8) << redCost << " dollars" << endl;

    cout << "   blue is" << setw(7) << blueCost << " dollars"

         << endl;

    cout << "   green is" << setw(6) << greenCost << " dollars"

         << endl;

    return 0;

}


	By default, consecutive integer, floating-point, and string values are output with no spaces between them.
	Manipulators are used to control the horizontal spacing of the output. (endl is one we’ve already seen)
	Manipulators we’ll use now
		endl first three defined in iostream
		fixed
		showpoint
		setw last two defined in iomanip
		setprecision


	setw (set width) lets us control how many character positions the next data item should occupy when it is output. (used for numbers and strings, not chars).
	The argument to setw is an integer fieldwidth specification, the data item is right-justified within the fieldwidth.
	If you don’t specify enough characters, the minimum number of characters is used anyway.


	Statement (ans = 33, num = 7132) Output ( means blank)
	cout << setw(4) << ans 33


	Statement (ans = 33, num = 7132) Output ( means blank))
	cout << setw(4) << ans << setw(5) 337132
	<< num


	Statement (ans = 33, num = 7132) Output ( means blank) cout << setw(4) << ans << setw(5) 337132Hi
	<< num << setw(4) << “Hi”;


	Statement (ans = 33, num = 7132) Output ( means blank) cout << setw(4) << ans << setw(5) 337132Hi
	<< num << setw(4) << “Hi”;
	cout << setw(2) << ans 33


	Statement (ans = 33, num = 7132) Output ( means blank) cout << setw(4) << ans << setw(5) 337132Hi
	<< num << setw(4) << “Hi”;
	cout << setw(2) << ans << setw(4) 337132
	<< num


	setw also works with floating-point numbers (remember that a decimal point is a character)
	If you don’t want numbers to appear in scientific notation, use fixed.
	If you want whole numbers printed with a .0 appended, use showpoint.
	If you want to control the number of decimal places that are displayed, use setprecision(n), where n is the number of decimal places desired. Unlike setw, setprecision stays in effect until you explicitly change it.


	Value
	of x Statement Output ( means blank)
	cout << fixed;
	310.0 cout << setw(10)
	<< setprecision(2) << x; 310.00


	Value
	of x Statement Output ( means blank) cout << fixed;
	310.0 cout << setw(10)
	<< setprecision(2) << x; 310.00
	310.00 cout << setw(10)
	<< setprecision(5) << x; 310.00000


	//****************************************************************
	// HouseCost program
	// This program computes the cost per square foot of
	// living space for a house, given the dimensions of
	// the house, the number of stories, the size of the
	// nonliving space, and the total cost less land
	//****************************************************************
	#include <iostream>
	#include <iomanip>// For setw() and setprecision()
	using namespace
	std;
	const float WIDTH = 30.0; // Width of the house
	const float LENGTH = 40.0; // Length of the house
	const float STORIES = 2.5; // Number of full stories
	const float NON_LIVING_SPACE = 825.0; // Garage, closets, etc.


	const float PRICE = 150000.0; // Selling price less land
	int main(){ float grossFootage; // Total square footage
	float livingFootage; // Living area
	float costPerFoot; // Cost/foot of living area
	cout << fixed << showpoint; // Set up floating pt.
	// output format

	grossFootage = LENGTH * WIDTH * STORIES;livingFootage =
	grossFootage - NON_LIVING_SPACE; costPerFoot = PRICE /
	livingFootage; cout << "Cost per square foot is “
	<< setw(6) << setprecision(2) << costPerFoot << endl;
	return 0;
	}


	int main()
	{
	float grossFootage; // Total square footage
	float livingFootage; // Living area
	float costPerFoot; // Cost/foot of living area

	cout << fixed << showpoint; // Set up floating pt.
	// output format

	grossFootage = LENGTH * WIDTH * STORIES;
	livingFootage = grossFootage - NON_LIVING_SPACE;
	costPerFoot = PRICE / livingFootage;

	cout << "Cost per square foot is "
	<< setw(6) << setprecision(2) << costPerFoot << endl;
	return 0;
	}


	Now, we consider four functions that operate on strings: length, size, find, substr
	The length and size functions both return an unsigned integer value equal to the number of characters in the string.
	The find function searches a string to find the first occurrence of a particular substring and returns an unsigned integer. If the substring is found, it returns the position where the match begins, if not found, it returns a special number.
	The substr function returns a particular substring of a string.


	If myName is a string variable, a call to length looks like this:
		myName.length()
	The length function requires no arguments, but you must still use parentheses.
	Also, length is value-returning, so the call must appear in an expression.


	Example:
	string firstName;
	string fullName;

	firstName = “Alexandra”;
	cout << firstName.length() << endl; // Prints 9
	fullName = firstName + “ Jones”;
	cout << fullName.length() << endl; // Prints 15


	string is a C++ class, which has data types and functions associated with it.
	Other classes may have a length function. To get the length function associated with string, we use the dot operator with a string variable.
	string has a data type associated with it to store a string length, string::size_type. Another class could also have size_type.
	string::size_type specifies the size_type associated with string.


	Example
		string firstName;
		string::size_type len;
		firstName = “Alexandra”;
		len = firstName.length();


	Example Usage
		string str1, str2;
		str1.find(“the”)
		str1.find(str2)
		str1.find(str2 + “abc”)
	If the string is not found, a special value (string::npos) is returned. The return value type is string::size_type.


	0123456789012345678901234567890
	str1 = “Programming and Problem Solving”;
	str2 = “gram”;

	Function Call Value Returned by Function
	str1.find(“and”) 12


	Sample function call:
		myString.substr(5, 20)
	Substr returns a string, the arguments to it are of type string::size_type.


	0123456789012345678901234567890
	myString = “Programming and Problem Solving”;

	Function Call String Returned by Function
	myString.substr(0, 7) “Program”


	//****************************************************************
	// This program demonstrates several string operations
	//****************************************************************
	#include <iostream>
	#include <string> // For string type
	using namespace std;
	int main()
	{
	string fullName;
	string name;
	string::size_type startPos;
	fullName = "Jonathan Alexander Peterson";
	startPos = fullName.find("Peterson");
	name = "Mr. " + fullName.substr(startPos, 8);
	cout << name << endl;
	return 0;
	}


	Problem: You are asked to calculate the total cost of painting traffic cones in three different colors. The cone company uses the area painted to estimate the total cost.
	Output: The surface area of the cone in square feet, and the costs of painting the cone in the three different colors, all displayed in floating point form to three decimal places.
	Discussion: Cones are measured in inches. A typical cone is 30 inches high and 8 inches in diameter. Red, blue, and green paint cost 10, 15, and 18 cents per square foot, respectively. The non-base surface area of a cone is pr(r² + h²)^1/2, where r is the radius of the cone and h is its height.


	//****************************************************************
	// This program computes the cost of painting traffic cones in
	// each of three different colors, given the height and diameter
	// of a cone in inches, and the cost per square foot of each of
	// the paints
	//****************************************************************
	#include <iostream>
	#include <iomanip> // For setw() and setprecision()
	#include <cmath> // For sqrt()

	using namespace std;

	const float HT_IN_INCHES = 30.0; // Height of a typical cone
	const float DIAM_IN_INCHES = 8.0; // Diameter of base of cone
	const float INCHES_PER_FT = 12.0; // Inches in 1 foot


	const float RED_PRICE = 0.10; // Price per square foot
	// of red paint
	const float BLUE_PRICE = 0.15; // Price per square foot
	// of blue paint
	const float GREEN_PRICE = 0.18; // Price per square foot
	// of green paint
	const float PI = 3.14159265; // Ratio of circumference
	// to diameter
	int main()
	{
	float heightInFt; // Height of the cone in feet
	float diamInFt; // Diameter of the cone in feet
	float radius; // Radius of the cone in feet
	float surfaceArea; // Surface area in square feet


	float redCost; // Cost to paint a cone red
	float blueCost; // Cost to paint a cone blue
	float greenCost; // Cost to paint a cone green

	cout << fixed << showpoint; // Set up floating-pt.
	// output format

	// Convert dimensions to feet
	heightInFt = HT_IN_INCHES / INCHES_PER_FT;
	diamInFt = DIAM_IN_INCHES / INCHES_PER_FT;
	radius = diamInFt / 2.0;

	// Compute surface area of the cone
	surfaceArea = PI * radius *
	sqrt(radiusradius + heightInFtheightInFt);


	// Compute cost for each color
	redCost = surfaceArea * RED_PRICE;
	blueCost = surfaceArea * BLUE_PRICE;
	greenCost = surfaceArea * GREEN_PRICE;

	// Print results
	cout << setprecision(3);
	cout << "The surface area is " << surfaceArea << " sq. ft."
	<< endl;
	cout << "The painting cost for" << endl << " red is";
	cout << setw(8) << redCost << " dollars" << endl;
	cout << " blue is" << setw(7) << blueCost << " dollars"
	<< endl;
	cout << " green is" << setw(6) << greenCost << " dollars"
	<< endl;
	return 0;
	}