C++ Part 12
// ---------- C++ TUTORIAL 12 ----------
// ---------- OPERATOR OVERLOADING ----------
#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <ctime>
#include <numeric>
#include <cmath>
// Needed for ostringstream
#include <sstream>
// Create a custom Box class with overloaded operators
class Box{
public:
double length, width, breadth;
// Used to hold a string representation of a box
std::string boxString;
Box(){
length = 1, width = 1, breadth = 1;
}
Box(double l, double w, double b){
length = l, width = w, breadth = b;
}
// You can define customer operators just like
// you define functions
// This is a unary operator because it operates
// on 1 object
// Other Unary Operators : --, *(pointer dereference),
// -> (Member Selection), !, & (Address of), +, -
Box& operator ++ (){
length++;
width++;
breadth++;
return *this;
}
// Creates a C string representation which is a
// pointer to an array that is null terminated
operator const char*() {
// Creates a stream that can be loaded with
// characters that can then be accessed as
// a string object
std::ostringstream boxStream;
boxStream << "Box : " <<
length << ", " <<
width << ", " <<
breadth;
// Return a string representation of the stream
boxString = boxStream.str();
// Returns the pointer to the string array
return boxString.c_str();
}
// Binary operators operate on 2 objects
// +, -, *, /, %, ==, !=, >, <, >=, <=, &&, ||,
// !, =, +=, -=, *=, /=, ^, [], &, |
// Let's add boxes
Box operator + (const Box& box2){
Box boxSum;
boxSum.length = length + box2.length;
boxSum.width = width + box2.width;
boxSum.breadth = breadth + box2.breadth;
return boxSum;
}
// Access items using a subscript operator
double operator [] (int x){
if(x == 0){
return length;
} else if(x == 1){
return width;
} else if(x == 2){
return breadth;
} else {
return 0;
}
}
// Check for box equality
bool operator == (const Box& box2){
return ((length == box2.length) &&
(width == box2.width) &&
(breadth == box2.breadth));
}
// Check for which is bigger
bool operator < (const Box& box2){
double thisSize = length + width + breadth;
double box2Size = box2.length + box2.width +
box2.breadth;
if (thisSize < box2Size){
return true;
} else {
return false;
}
}
bool operator > (const Box& box2){
double thisSize = length + width + breadth;
double box2Size = box2.length + box2.width +
box2.breadth;
if (thisSize > box2Size){
return true;
} else {
return false;
}
}
// Overload the assignment operator
void operator = (const Box& boxToCopy){
length = boxToCopy.length;
width = boxToCopy.width;
breadth = boxToCopy.breadth;
}
};
int main()
{
Box box(10,10,10);
// Will increment all values in the box by 1
++box;
std::cout << box << "\n";
// Add boxes
Box box2(5,5,5);
std::cout << "Box1 + Box2 = " <<
box + box2 << "\n";
// Access data with subscript operator
std::cout << "Box Length : " <<
box[0] << "\n";
// Displays true or false for bolleans
std::cout << std::boolalpha;
std::cout << "Are boxes equal : " <<
(box == box2) << "\n";
// Is box < box2
std::cout << "Is box < box2 : " <<
(box < box2) << "\n";
// Is box > box2
std::cout << "Is box < box2 : " <<
(box > box2) << "\n";
box = box2;
std::cout << box << "\n";
return 0;
}
// ---------- OPERATOR OVERLOADING ----------
// ---------- FILE I/O & PROBLEM ----------
#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <ctime>
#include <numeric>
#include <cmath>
#include <sstream>
// iostream allows use to read from the standard
// input (keyboard) and write to the standard output
// (console)
// fstream is needed for working with files
#include <fstream>
// ----- PROBLEM FUNCTION PROTOTYPE -----
std::vector<std::string> StringToVector(std::string,
char separator);
// ----- END OF PROBLEM FUNCTION PROTOTYPE -----
int main()
{
std::ofstream writeToFile;
std::ifstream readFromFile;
std::string txtToWrite = "";
std::string txtFromFile = "";
// We open the file by providing a name and then either
// ios::app : Append to the end of the file
// ios::trunc : If the exists delete content
// ios::in : Open file for reading
// ios::out : Open file for writing
// ios::ate : Open writing and move to the end of the file
writeToFile.open("test.txt", std::ios_base::out |
std::ios_base::trunc);
if(writeToFile.is_open()){
// You can write with the stream insertion operator
writeToFile << "Beginning of File\n";
// You can write data in a string
std::cout << "Enter data to write : ";
getline(std::cin, txtToWrite);
writeToFile << txtToWrite;
// Close the file
writeToFile.close();
}
// Open the file for reading
readFromFile.open("test.txt", std::ios_base::in);
if(readFromFile.is_open()){
// Read text from file
while(readFromFile.good()){
getline(readFromFile, txtFromFile);
// Print text from file
std::cout << txtFromFile << "\n";
// ----- PROBLEM -----
// After each line print both the number of
// words in each line and the average word length
std::vector<std::string> vect =
StringToVector(txtFromFile, ' ');
int wordsInLine = vect.size();
std::cout << "Words in Line : " <<
wordsInLine << "\n";
int charCount = 0;
for(auto word: vect){
for(auto letter: word){
charCount++;
}
}
int avgNumChars = charCount/wordsInLine;
std::cout << "Avg Word Length : " <<
avgNumChars << "\n";
// ----- END OF PROBLEM -----
}
readFromFile.close();
}
return 0;
}
// ----- PROBLEM FUNCTION -----
std::vector<std::string> StringToVector(std::string theString,
char separator){
// Create a vector
std::vector<std::string> vecsWords;
// A stringstream object receives strings separated
// by a space and then spits them out 1 by 1
std::stringstream ss(theString);
// Will temporarily hold each word in the string
std::string sIndivStr;
// While there are more words to extract keep
// executing
// getline takes strings from a stream of words stored
// in the stream and each time it finds a blanks space
// it stores the word proceeding the space in sIndivStr
while(getline(ss, sIndivStr, separator)){
// Put the string into a vector
vecsWords.push_back(sIndivStr);
}
return vecsWords;
}
// ----- END OF PROBLEM FUNCTION -----
// ---------- FILE I/O & PROBLEM ----------