C++ For Java Programmers

C++ is a powerful object oriented language, which is known for its performance, efficiency, and flexibility due to its ability to manipulate low-level memory. The C++ syntax is quite similar to Java syntax so Java programmers will find it easy to pick up the language.

Resources

• cplusplus.com
• cprogramming.com

• C++ Language tutorial , by Juan Solie, 2007
• Learn C++ programming language , by Tutorialspoint

Tips for leaning C++

1. Always comment so it is easier to update your codes later.
2. Learn the syntax carefully. Although C++ syntax is quite similar to Java syntax, there are certain differences.
3. Differentiate between call by value and call by reference, since this concept is emphasized in C++.
4. Data collection in C++ is also difference from in Java.
5. Because C++ is not as good as Java in finding code errors, being careful in each small step is necessary.
6. Keep practicing everyday by reading books and doing exercises.

Exercises

1. Write a program to convert temperature from Celsius to Fahrenheit and vice versa.
   Toggle answer

   
   #include <iostream>
   using namespace std;
   
   // function change Celsius to Fahrenheit
   double c_to_f(double c){
       return c * 1.8 + 32;
   }
   
   // function change Celsius to Fahrenheit
   double f_to_c(double f){
       return (f-32) * 5 / 9;
   }
   
   int main(){
       double c;
       double f;
       cout << "Enter c degree values: ";
   
       // print result
       for(int i = 0; i < 5; i++){
           cin >> c;
           cout << c << " degree C equals " << c_to_f(c) << " degree F" << endl;
       }
       cout << "Enter f degree values: ";
       for(int i = 0; i < 5; i++){
           cin >> f;
           cout << f << " degree F equals " << f_to_c(f) << " degree C" << endl;
       }
   }
                       

2. Write a program that will terminate if user type 5 otherwise keep running.
   Toggle answer

   
   #include <iostream>
   using namespace std;
   
   int main(){
       int a = 1;
       while(a!=5){
           cin >> a;
           // check the input is not digit
           if(cin.fail()){
               cout << "Invalid input"<< endl;
               cin.clear();
               cin.ignore(10000, '\n');
           }
       }
       cout << "It cannot be 5"<< endl;
       return 0;
   }
                       

3. Write a program to calculate area and circumference of circle for given radius.
   Toggle answer

   
   #include <iostream>
   #include <iomanip>
   using namespace std;
   
   // function to calculate area and circumference
   void areaAndCircumference(double r, double* a, double *c){
       const double pi = 3.1416;
       *a = pi * r * r;
       *c = 2.0 * pi * r;
       r = 0;
   }
   
   int main(){
       double r, c, a;
       cout << "Enter the radius: ";
       cin >> r;
       // call function by references
       areaAndCircumference(r, &a, &c);
       cout << "Area: " << a << ". Circumference: " << c << endl;;
       cout << r << endl;
       return 0;
   }
                   

4. Write a program to print all permutation of the given string
   Toggle answer

   
   #include <iostream>
   #include <string>
   using namespace std;
   
   // function to swap two element in array
   void swap(char *a, char *b){
       char temp;
       temp = *a;
       *a = *b;
       *b = temp;
   }
   
   // recursive function to print all permutation
   void recursive_permutation(char *arr, int len, int position){
       // base case
       if(position == len - 1){
           printf("%s\n", arr);
       }
       // recursive
       else{
           for(int i = position; i < len; i++){
               swap((arr+position), (arr+i));
               recursive_permutation(arr, len, position+1);
               swap((arr+position), (arr+i));
           }
       }
   }
   
   int main(){
       char array[] = "abcd";
       int len = strlen(array);
       recursive_permutation(array, len, 0);
   }
                   

5. Write a program to make a guessing game with the following rules:
    Part 1: Computer generate a random number from 1 to 100. You guess until correct.
    Part 2: User think a number from 1 to 100. Train computer to guess correctly in less than 8 guesses.
   Toggle answer

   
   #include <iostream>
   using namespace std;
   
   // Part 1: User guesses
   int guessNum(){
       int value;
       int count = 0;
       int v = rand() % 100 + 1;
       cout<< "Guess a number: ";
       cin>>value;
       while (true){
           count ++;
           if(value < v){
               cout << "Too low" << endl;
           }
           else if(value > v){
               cout << "Too high" << endl;
           }
           else{
               cout << "You are correct after " << count << " guesses" << endl;
               return 0;
           }
           cin>>value;
       }
       return 0;
   }
   
   // Part 2: Computer guesses
   int guessUserNum(){
       char decide;
       int count = 0;
       int min = 0;
       int max = 100;
       while (true){
           int guess = (min+max)/2;
           cout << "Computer guesses " << guess << ". Is it higher(h), lower(l) than your number, or correct(c-default value)" << endl;
           count++;
           cin >> decide;
           if(decide == 'l'){
               min = guess + 1;
           }
           else if(decide == 'h'){
               max = guess - 1;
           }
           else{
               cout << "Correct after " << count << " guesses" << endl;
               return 0;
           }
   
       }
       return 0;
   }
   
   int main(){
       guessNum();
       guessUserNum();
   }
                   

6. Write a program that asks user to enter the number of pancakes eaten by 10 different people.
     Part 1: Print the person eat the least and eat the most along with their number of pancakes.
     Part 2: Display list of people in order of number of pancakes eaten.
     Sample run:
        Person 4: ate 10 pancakes
        Person 3: ate 7 pancakes
        Person 8: ate 4 pancakes
        ........................
        Person 5: ate 0 pancakes
   Toggle answer

   
   #include <iostream>
   using namespace std;
   
   // function to find people eat the most pancake
   int findMax(int arr[], int len){
       int max;
       int maxIndex;
       max = arr[0];
       for(int i = 1; i < len; i++){
           if(arr[i]>max){
               max = arr[i];
               maxIndex = i;
           }
       }
       return maxIndex;
   }
   
   // function to find people eat the least pancake
   int findMin(int arr[], int len){
       int min;
       int minIndex;
       min = arr[0];
       for(int i = 0; i < len; i++){
           if(arr[i] < min){
               min = arr[i];
               minIndex = i;
           }
       }
       return minIndex;
   }
   
   // display people in order
   int find_order(int arr[], int len, int indexes[]){
       int result[len];
       for(int i = 0; i < len -1; i++){
           int maxIndex = i;
           for(int j = i+1; j < len; j++){
               if(arr[maxIndex] < arr[j]){
                   maxIndex = j;
               }
           }
           int temp = arr[i];
   	    arr[i] = arr[maxIndex];
   	    arr[maxIndex] = temp;
   
   	    temp = indexes[i];
   	    indexes[i] = indexes[maxIndex];
   	    indexes[maxIndex] = temp;
       }
       return 0;
   }
   
   int main(){
       int a, value;
       int len = 10;
       int arr[len];
       for(int i = 0; i < len; i++){
           cout << "Enter value: ";
           cin >> value;
           arr[i] = value;
       }
   
       int minIndex = findMin(arr, len);
       cout << "Min is " << arr[minIndex] << endl;
       cout << "Person " << minIndex + 1 << " ate " << arr[minIndex] << ", the least number of pancake" << endl;
   
       int maxIndex = findMax(arr, len);
       cout << "Max is " << arr[maxIndex] << endl;
       cout << "Person " << maxIndex + 1 << " ate " << arr[maxIndex] << ", the most number of pancake" << endl;
   
       cout << "Display in order: " << endl;
   
       int sorted_array[len];
       int sorted_indexes[len];
       for(int i = 0; i < len; i++){
           sorted_array[i] = arr[i];
           sorted_indexes[i] = i;
       }
       find_order(sorted_array, len, sorted_indexes);
       for(int i = 0; i < len; i++){
           cout<< "Person " << sorted_indexes[i] + 1 <<  " ate: " << sorted_array[i] << " pancakes" << endl;
   
       }
       return 0;
   }