Exercise 14.1 (Completed)

1. (Practice) Enter and run Program 14.2.

//Done!!

#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string message;    // declare a string object
	cout << "Enter a string : \n";
	getline(cin, message);
	cout << "The string just entered is : \n"
		<< message << endl;
	system("PAUSE");
	return 0;
}

2. (Practice) Determine the value of text.at(0), text.at(3), and text.at(10), assuming
for each one that text is each of the following strings:
a. Now is the time

text.at(0) = N
text.at(3) = (space)
text.at(10) = t

b. Rocky raccoon welcomes you

text.at(0) = R
text.at(3) = k
text.at(10) = o

c. Happy Holidays

text.at(0) = H 
text.at(3) = p 
text.at(10) = a

d. The good ship

text.at(0) = T
text.at(3) = (space)
text.at(10) = i

3. (Practice) Enter and run Program 14.5.

//Done!!
#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string str = "Counting the number of vowels";
	int i, numChars;
	int vowelCount = 0;
	cout << "The string : " << str << endl;
	numChars = int(str.length());
	for (i = 0; i < numChars; i++)
	{
		switch (str.at(i))   // here's where a character is retrieved
		{
		case 'a':
		case 'e':
		case 'i':
		case 'o':
		case 'u':
			vowelCount++;
		}
	}
	cout << "has " << vowelCount << " vowels." << endl;
	system("PAUSE");
	return 0;
}

4. (Modify) Modify Program 14.5 to count and display the numbers of each vowel contained in
the string.

#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string str = "Counting the number of vowels";
	int i, numChars;
	int vowelCount5 = 0;
	int vowelCount1 = 0;
	int vowelCount2 = 0;
	int vowelCount3 = 0;
	int vowelCount4 = 0;
	cout << "The string : " << str << endl;
	numChars = int(str.length());
	for (i = 0; i < numChars; i++)
	{
		switch (str.at(i))   // here's where a character is retrieved
		{
		case 'a':
		   vowelCount1++;
		   break;
		case 'e':
		    vowelCount2++;
			break;
		case 'i':
		    vowelCount3++;
			break;
		case 'o':
		    vowelCount4++;
			break;
		case 'u':
			vowelCount5++;
			break;
		}
	}
	cout << "has " << vowelCount1 << " A vowels" << endl;
		cout << vowelCount2 << " E vowels" << endl;
		cout << vowelCount3 << " I vowels" << endl;
		cout << vowelCount4 << " O vowels" << endl;
		cout << vowelCount5 << " U vowels" << endl;
	system("PAUSE");
	return 0;
}

5. (Modify) Modify Program 14.5 to display the number of vowels in a user-entered string.

#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string str;
	int i, numChars;
	int vowelCount = 0;
	cout << "Enter your String " << endl;
	cin >> str;
	cout << "The string : " << str << endl;
	numChars = int(str.length());
	for (i = 0; i < numChars; i++)
	{
		switch (str.at(i))   // here's where a character is retrieved
		{
		case 'a':
		case 'e':
		case 'i':
		case 'o':
		case 'u':
			vowelCount++;
		}
	}
	cout << "has " << vowelCount << " vowels." << endl;

	system("PAUSE");
	return 0;
}


6. (Program) Using the at() method, write a C++ program that reads in a string by using
getline(), stores the string in a string object named message, and then displays the
string in reverse order. (Hint: After the string has been entered and saved, retrieve and display
characters, starting from the end of the string. The last character is located at the position
message.length() - 1.)

#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string message;
	getline(cin, message);
	for (int i = message.length()-1; i < message.length(); --i){
		cout << message.at(i)<< endl;
	}

	system("PAUSE");
	return 0;
}

7. (Program) Write a C++ program that accepts both a string and a single character from the
user. The program should determine how many times the character is contained in the string.
(Hint: Search the string by using the find(str,ƒind) method. This method should be used
in a loop that starts the index value at 0 and then changes the index value to 1 past the index
of where the char was last found.)

#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	int i, number = 0;
	string str;
	char letter;
	cin >> str;
	cin >> letter;
	int numChars = int(str.length());

	cout << "The original string is  " << str << endl;
	for (i = 0; i < numChars; i++){
	
		if (str.at(i) == letter){
			number++;
		}
}
	
	cout << "The number of letters is " << number << endl;
	system("PAUSE");
	return 0;
}

8. (Practice) Enter and run Program 14.6.

//Done!!

#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string str = "This cannot be";
	cout << "The original string is : " << str << endl
		<< "  and has " << int(str.length()) << " characters." << endl;
	// insert characters
	str.insert(4, " I know");
	cout << "The string, after insertion, is: " << str << endl
		<< "  and has " << int(str.length()) << " characters." << endl;
	// replace characters
	str.replace(12, 6, "to");
	cout << "The string, after replacement, is: " << str << endl
		<< "  and has " << int(str.length()) << " characters." << endl;
	// append characters
	str = str + " correct";
	cout << "The string, after appending, is: " << str << endl
		<< "  and has " << int(str.length()) << " characters." << endl;
	system("PAUSE");
	return 0;
}

9. (Practice) Enter and run Program 14.7.

//Done!!
#include "stdafx.h" 
#include <iostream>
#include <string>
using namespace std;
int main()
{
	string string1 = "LINEAR PROGRAMMING THEORY";
	string s1, s2, s3;
	int j, k;
	cout << "The original string is " << string1 << endl;
	j = int(string1.find('I'));
	cout << "  The first position of an 'I' is " << j << endl;
	k = int(string1.find('I', (j + 1)));
	cout << "  The next position of an 'I' is " << k << endl;
	j = int(string1.find("THEORY"));
	cout << "  The first location of \"THEORY\" is " << j << endl;
	k = int(string1.find("ING"));
	cout << "  The first index of \"ING\" is " << k << endl;
	// now extract three substrings
	s1 = string1.substr(2, 5);
	s2 = string1.substr(19, 3);
	s3 = string1.substr(6, 8);
	cout << "The substrings extracted are : " << endl
		<< "  " << s1 + s2 + s3 << endl;

	system("PAUSE");
	return 0;
}