Question

C++

Modify this program (or create your own) so that it performs the following tasks: 1. Insert the numbers into the list in sorted order (ascending). This will require you to keep the list sorted as you continue to insert new numbers. 2. When adding a new number, first check to see whether it is larger than the last number currently in the list. If it is, add it directly to the end of the list, i.e., do not traverse the list to get to the end of the list and then add it. Should this improve the average performance of the list building portion of your code? If so, when? Be prepared to discuss this in class. 3. If the new number is less than the last number in the list, start at the head of the list and scan the list until you find the next larger number. Insert your new number into the list at that point. 4. Check for duplicates; do not add a number to the list more than once. 5. After inserting all the random numbers, count the number of elements (numbers) in the list and report it. 6. Print the list of numbers to the console, 5 numbers to a row. 7. Add a function that will search for a specified number. Search for a minimum of 3 different numbers and report whether the number was found or not.

#include <iostream>
#include <iomanip> //setw
using namespace std;


// ----- globals ----- //
const int maxNumsInaRow = 5; //number of numbers to print in a single row
const int numsToGenerate = 25; //number of random numbers to generate
const int maxValueToGenerate = 50; //max value of a number to generate

// ----- basic utility routines - these are shown for examples only ----- //

bool dbgprinting = false; //set to true to see all debugging msgs

void dprint(string msg,int val) {
   if (dbgprinting)
      cout << msg << " " << val << endl;
}//dprint


void dprint(string msg,string str2) {
   if (dbgprinting)
      cout << msg << " " << str2 << endl;
}//dprint


void show(string msg,string msg2="") {
   cout << msg << " " << msg2 << endl;
} //show

void show(string msg,int num) {
   cout << msg << " " << num << endl;
} //show

void ckError(bool condition,string errorString) {
   if (condition) {
      cout << errorString << endl;
      system("pause");
   }
} //ckError

void line() {
   cout << "---------------------------------------" << endl;
} //line


// --------------------------------------------------------//
struct Number { //this is the main data structure for this program
   int numValue;; //the number's value
   Number *nextNumber; //points to next Number in the list, or nullptr if none
};

// declare the necessary pointers for the Number list
Number *listHead; //always points to the first element in the list
Number *listTail; //always points to the last element in the list
// --------------------------------------------------------//


int countNumbersInList() {
   int count=0;
   Number* aNumberPtr = listHead;
   do {
      dprint("counting ",aNumberPtr->numValue);
      count++;
      aNumberPtr = aNumberPtr->nextNumber;
   } while (aNumberPtr != nullptr);
   return count;
} //countNumbersInList


void showAllNumbers() {
        static int rowLength = 0; //this is just for pretty-printing
   Number *nextNum; //for traversing the Number list

   line();
   if (listHead == nullptr) {
      show("There are no numbers in the list");
      return;
   };

   show("Number of numbers in the list = ",countNumbersInList());
   nextNum = listHead; //ok, now let's show each Number
   do {
      cout << setw(6) << nextNum->numValue;
      rowLength++;
      if ((rowLength % maxNumsInaRow) == 0)
                        cout << endl; //advance to next line
      nextNum = nextNum->nextNumber;
   } while (nextNum != nullptr);
   cout << endl;
} //showAllNumbers


// this routine doesn't insert the numbers in numeric order - fix it
void addNumberToList(int numberToAdd) {
   dprint("Adding a new Number:",numberToAdd);
   Number* newNum;
   newNum = new Number;
   newNum->numValue = numberToAdd;
   newNum->nextNumber = listHead;
   listHead = newNum;
} //addNumberToList


bool findANumber(int theNumberToFind) {
   dprint("Entering findANumber ",theNumberToFind);
   Number *curNumber = listHead;
   while (curNumber != nullptr) {
      if (curNumber->numValue == theNumberToFind) {
         show("Yes, we found the Number:",theNumberToFind);
         return true;
      }
      curNumber = curNumber->nextNumber;
   }
   show("Sorry, we couldn't find the Number:",theNumberToFind);
   return false;
} //findANumber


// ----- main function ----- //
main() {

   srand(time(0));

   //define an empty list
   listHead = nullptr;
   listTail = nullptr;

   showAllNumbers(); //there should be none

        //generate some random numbers and insert them into the list
   for (int n=0; n<numsToGenerate; n++)
      addNumberToList((rand() % maxValueToGenerate)+1);

   showAllNumbers(); //there should be some now, but not in order :-(

   //now search for some numbers, no need to count duplicates
   line();
   findANumber(16);
   findANumber(32);
   findANumber(-24); //note that we can search for any number

   return 0;
} //main

Answer 1

I have made few changes in your code and have written the code for addNumberToList.

Note: While initialising the Struct data structure, it is a better practise to initialise the pointer as NULL. This was the reason why your countNumbersInList() and showAllNumbers() were having segmentation fault.

#include <iostream>
#include <iomanip> //setw
using namespace std;

// ----- globals ----- //
const int maxNumsInaRow = 5; //number of numbers to print in a single row
const int numsToGenerate = 25; //number of random numbers to generate
const int maxValueToGenerate = 50; //max value of a number to generate

// ----- basic utility routines - these are shown for examples only ----- //

bool dbgprinting = false; //set to true to see all debugging msgs

void dprint(string msg,int val) {
if (dbgprinting)
cout << msg << " " << val << endl;
}//dprint

void dprint(string msg,string str2) {
if (dbgprinting)
cout << msg << " " << str2 << endl;
}//dprint

void show(string msg,string msg2="") {
cout << msg << " " << msg2 << endl;
} //show

void show(string msg,int num) {
cout << msg << " " << num << endl;
} //show

void ckError(bool condition,string errorString) {
if (condition) {
cout << errorString << endl;
system("pause");
}
} //ckError

void line() {
cout << "---------------------------------------" << endl;
} //line

// --------------------------------------------------------//
struct Number { //this is the main data structure for this program
int numValue;; //the number's value
Number *nextNumber = NULL; //points to next Number in the list, or nullptr if none
};

// declare the necessary pointers for the Number list
Number *listHead; //always points to the first element in the list
Number *listTail; //always points to the last element in the list
// --------------------------------------------------------//

int countNumbersInList() {
int count=0;
Number* aNumberPtr = listHead;
do {
dprint("counting ",aNumberPtr->numValue);
count++;
aNumberPtr = aNumberPtr->nextNumber;
} while (aNumberPtr != NULL);
return count;
} //countNumbersInList

void showAllNumbers() {
static int rowLength = 0; //this is just for pretty-printing
Number *nextNum; //for traversing the Number list

line();
if (listHead == NULL) {
show("There are no numbers in the list");
return;
}

show("Number of numbers in the list = ",countNumbersInList());
nextNum = listHead; //ok, now let's show each Number
do {
cout << setw(6) << nextNum->numValue;
rowLength++;
if ((rowLength % maxNumsInaRow) == 0)
cout << endl; //advance to next line
nextNum = nextNum->nextNumber;
} while (nextNum != nullptr);
cout << endl;
} //showAllNumbers

// this routine doesn't insert the numbers in numeric order - fixed it ;)
void addNumberToList(int numberToAdd) {
dprint("Adding a new Number:",numberToAdd);
Number* temp = new Number;
temp->numValue = numberToAdd;
if(listHead == NULL){
listHead = temp;
listTail = temp;
return;
}

if(numberToAdd > listTail->numValue){
listTail->nextNumber = temp;
listTail = temp;
return;
}
if(numberToAdd < listHead->numValue){
temp->nextNumber = listHead;
listHead = temp;
return ;
}
Number* temp1 = listHead;
Number* prev = temp1;
while(temp1->numValue <= numberToAdd && temp1 != NULL){
if(temp1->numValue == numberToAdd){
return;
}
prev = temp1;
temp1 = temp1->nextNumber;
}
prev->nextNumber = temp;
temp->nextNumber = temp1;
return;

} //addNumberToList

bool findANumber(int theNumberToFind) {
dprint("Entering findANumber ",theNumberToFind);
Number *curNumber = listHead;
while (curNumber != NULL) {
if (curNumber->numValue == theNumberToFind) {
show("Yes, we found the Number:",theNumberToFind);
return true;
}
curNumber = curNumber->nextNumber;
}
show("Sorry, we couldn't find the Number:",theNumberToFind);
return false;
} //findANumber

// ----- main function ----- //
main() {

srand(time(0));

//define an empty list
listHead = NULL;
listTail = NULL;

showAllNumbers(); //there should be none

//generate some random numbers and insert them into the list
for (int n=0; n<numsToGenerate; n++)
addNumberToList((rand() % maxValueToGenerate)+1);
  
showAllNumbers(); //there should be some now, and now in order ;)

//now search for some numbers, no need to count duplicates
line();
findANumber(16);
findANumber(32);
findANumber(-24); //note that we can search for any number

return 0;
}