Question

Use c-strings for the following project:

Write a C++ program that declares an array containing up to a maximum of 20 sentences, each sentence of maximum 81 characters long, using c-strings. Continue reading sentences from the user and store them in the array of sentences, until the user enters a NULL string for the sentence or 20 sentences have been entered.

Then, one by one, display each sentence entered by the user and present the following menu of operations on each sentence:

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

If option 1 is selected, the program calls a function which takes the string and a character and returns either the index within the string of the first occurrence of the character or -1 if it could not be found. Print the location it was first found or that it was not found. If found, print how many times it was found.

If option 2 is selected, the program calls a function that takes a string, an integer for the position of the character to be changed and a character and changes the character located at the given position in the string to the given character. Keep looping until a valid value is entered for the position.

If option 3 is selected, a function is called which takes a string and an integer n and displays the first n characters of the string. Keep looping until a valid value is entered for the number of characters to be printed.

If option 4 is selected, a function is called which takes a string and an integer n and displays the last n characters of the string. Keep looping until a valid value is entered for the number of characters to be printed.

If option 5 is selected, a function is called which takes a string and two integers and displays all the characters that lie between the two indices, inclusive. Keep looping until a valid value is entered for both numbers.

If option 6 is selected, a function is invoked which takes a string and nulls the string meaning it makes it a 0-length string. If it already has 0 length, it must display a message saying that.

If option 7 is selected at any time, the program exits the loop and displays all the sentences entered, including any modification done by the user.

If the user has not existed and all sentences have been displayed and processed, the program must display all the sentences again, including any changes that might have been made to them by the user.

Upload just the cpp file using the Browse and Upload buttons. (The cpp file is in the folder that has the name you gave the project.

The following is a Sample execution of the program:

Enter up to 20 sentences - when done, Press ENTER:

1. My roommate is not home right now.

2. I am a student at Valley College.

3. My brother is not home.

4. Programming in C++ is fun.

5. My sister has a new job.

6. Valley Glen, CA, is a residential area.

7. I'm hungry; Let's order a pizza.

8. I only have $51.32 on me.

9. My brother Joe just got married.

10. He lives in Ohio.

11. This is just another simple string.

12. [ENTER]

Here is sentence 1:

My roommate is not home right now.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 1

Please enter the character to search for: o

There are 5 o's in the sentence, with the 1st one at index 4.

Here is sentence 2:

I am a student at Valley College.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 1

Please enter the character to search for: v

There are no v's in "I am a student at Valley College."

Here is sentence 3:

My brother is not home.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 2

What is the index of the character you want to change? 21

What character do you want in that position? w

The new string is "My brother is now home"

Here is sentence 4:

Programming in C++ is fun.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 2

What is the index of the character you want to change? 30

What character do you want in that position? X

That position is outside the bounds of the string. String unchanged.

Here is sentence 5:

My sister has a new job.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 3

How many characters from the beginning of the string do you want to display? 8

My broth

Here is sentence 6:

Valley Glen, CA, is a residential area.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 3

How many characters from the beginning of the string do you want to display? 32

Error: too many characters.

Here is sentence 7:

I'm hungry; Let's order a pizza.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 4

How many characters from the end of the string do you want to display? 10

r a pizza.

Here is sentence 8:

I only have $51.32 on me.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 4

How many characters from the end of the string do you want to display? 30

Error: too many characters.

Here is sentence 9:

My brother just got married.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 5

Please enter the beginning index: 5

Please enter the ending index: 12

other Ju

Here is sentence 10:

He lives in Ohio.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 5

Please enter the beginning index: 5

Please enter the ending index: 32

Error: one or more indices are outside the bounds of the array.

Here is sentence 11:

This is just another simple string.

What do you want to do?

1. Search for a character in the sentence

2. Change a character within the sentence

3. Display the first n characters of the sentence

4. Display the last n characters of the sentence

5. Display all characters that lie between two given indices

6. Null the string

7. Exit

Choice: 6

The string is now Null.

My roommate is not home right now.

I am a student at Valley College.

My brother is now home.

Programming in C++ is fun.

My sister has a new job.

Valley Glen, CA, is a residential area.

I'm hungry; Let's order a pizza.

I only have $51.32 on me.

My brother Joe just got married.

He lives in Ohio.

Press any key to continue . . .

Answer 1

Code

#include<iostream>
#include<string.h>

using namespace std;
#define NUM_STRINGS 20
#define NUM_CHAR 81
int getSentences(char [][NUM_CHAR]);
int printMenu();
int findChar(char [],char);
void changeCharcter(char [],char,int);
void displayFirstNChar(char [],int);
void displayLastNChar(char [],int);
void displayCharBetweenIndices(char [],int,int);
void nullTheSentence(char []);
int main()
{
   char sentences[NUM_STRINGS][NUM_CHAR];
   int number_of_sentence;
   int choice,pos;
   char ch;

   number_of_sentence=getSentences(sentences);
   memset(&sentences[number_of_sentence], 0, sizeof(sentences[number_of_sentence]));
   for(int i=0;i<number_of_sentence;i++)
   {
       cout<<"Here is sentence "<<(i+1)<<":"<<endl;
       cout<<sentences[i]<<endl;
       choice=printMenu();
       switch (choice)
       {
       case 1:
           cout<<"Please enter the character to search for: ";
           cin>>ch;
           pos=findChar(sentences[i],ch);
           if(pos>0)
               cout<<"with the 1st one at index "<<pos<<".\n";
           break;
       case 2:
           cout<<"What is the index of the character you want to change?";
           cin>>pos;
           cout<<"What character do you want in that position?";
           cin>>ch;
           changeCharcter(sentences[i],ch,pos);
           break;
       case 3:
           cout<<"How many characters from the beginning of the string do you want to display?";
           cin>>pos;
           displayFirstNChar(sentences[i],pos);
           break;
       case 4:
           cout<<"How many characters from the end of the string do you want to display?";
           cin>>pos;
           displayLastNChar(sentences[i],pos);
           break;
       case 5:
           int startPos,endPos;
           cout<<"Please enter the beginning index: ";
           cin>>startPos;
           cout<<"Please enter the ending index: ";
           cin>>endPos;
           displayCharBetweenIndices(sentences[i],startPos,endPos);
           break;
       case 6:
           nullTheSentence(sentences[i]);
           break;
       case 7:
           break;
       default:
           cout<<"Invalid choice."<<endl;
           break;
       }
   }
   cout<<"\n\n";
   int i=0;
   while(true)
   {
       int len=strlen(sentences[i]);
       if(len==0)
           break;
       i++;
       cout<<sentences[i]<<endl;
   }
   return 1;
}
int printMenu()
{
   int choice;
   cout<<"What do you want to do?"<<endl;
   cout<<"1. Search for a character in the sentence"<<endl;
   cout<<"2. Change a character within the sentence"<<endl;
   cout<<"3. Display the first n characters of the sentence"<<endl;
   cout<<"4. Display the last n characters of the sentence"<<endl;
   cout<<"5. Display all characters that lie between two given indices"<<endl;
   cout<<"6. Null the string"<<endl;
   cout<<"7. Exit"<<endl;
   cout<<"Choice: ";
   cin>>choice;
   return choice;
}
int getSentences(char sen [][NUM_CHAR])
{
   char input[81];

   int count=0;
   cout<<"Enter up to 20 sentences - when done, Press ENTER:"<<endl;
   while(count<NUM_STRINGS)
   {
       cout<<(count+1)<<". ";
       gets(input);
       if(strcmp(input,"")==0)
           break;
       strcpy(sen[count],input);
       count++;
   }
   return count;
}

int findChar(char sen[],char c)
{
   int count=0;
   bool firstFind=true;
   int index;
   for(int i=0;sen[i]!='\0';i++)
   {
       if(sen[i]==c)
       {
           if(firstFind)
           {
               index=i;
               firstFind=false;
           }
           count++;
       }
   }
   if(count==0)
   {
       cout<<"There are no "<<c<<"'s in \""<<sen<<"\""<<endl;
           return -1;
   }
   cout<<"There are "<<count<<" "<<c<<"'s in the sentence, ";
   return index;
}
void changeCharcter(char sen[],char c,int pos)
{
   int len=strlen(sen);
   if(pos>=0 && pos<len)
   {
       sen[pos]=c;
       cout<<"The new string is \""<<sen<<"\""<<endl;
       return;
   }
   cout<<"That position is outside the bounds of the string. String unchanged."<<endl;
}
void displayFirstNChar(char sen[],int pos)
{
   int len=strlen(sen);
   if(pos<len)
   {
       for(int i=0;i<pos;i++)
           cout<<sen[i];
       cout<<endl;
       return;
   }
   cout<<"Error: too many characters."<<endl;
}

void displayLastNChar(char sen[],int pos)
{
   int len=strlen(sen);
   if(pos<len)
   {
       for(int i=len-pos;i<len;i++)
           cout<<sen[i];
       cout<<endl;
       return;
   }
   cout<<"Error: too many characters."<<endl;
}
void displayCharBetweenIndices(char sen[],int start,int end)
{
   int len=strlen(sen);
   if(start>=0 && start<len && end>start && end<len)
   {
       for(int i=start;i<end;i++)
           cout<<sen[i];
       cout<<endl;
       return;
   }
   cout<<"Error: one or more indices are outside the bounds of the array."<<endl;
}
void nullTheSentence(char sen[])
{
   int len=strlen(sen);
   if(len!=0)
   {
       memset(&sen, 0, sizeof(sen));
       cout<<"The string is now Null."<<endl;
       return;
   }
   cout<<"String is already null"<<endl;
}

output

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