class istream help me understand this

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#include <iostream>
#include <stdlib.h>
using namespace std;

//Class definition
class Complex
{
	private:
		int a, b;
		
	public:	
		Complex();
		Complex(int, int);
		Complex operator + (Complex);
		Complex operator - (Complex);
		Complex operator * (int);
		friend istream& operator >> (istream &Input, Complex &cmplx);
		friend ostream& operator << (ostream &Output, Complex &cmplx);
};

//A function that prints a menu.
void printMenu();

//Main function
int main()
{	

	cout << "The program does operations for complex numbers." << endl
		 << "PUT AS MANY SPACES AS YOU WANT! JUST DO NOT SEPERATE A NUMBER." 
		 << endl << endl;
	

	int repeat = 1;
	do{		              		
	
	int Operation;			
	printMenu();
	cin >> Operation;
	cin.ignore();			
	
	Complex c1, c2, c_ans;	
	
	if (Operation == 1)
	{
		cout << "Enter the first complex number: ";
		cin >> c1;
		cout << "Enter the second complex number: ";
		cin >> c2;
		c_ans = c1 + c2;
		cout << "( " << c1 << " ) + ( " << c2 << " ) = " << c_ans << endl;
	}
	else if (Operation == 2)
	{
		cout << "Enter the first complex number: ";
		cin >> c1;
		cout << "Enter the second complex number: ";
		cin >> c2;
		c_ans = c1 - c2;
		cout << "( " << c1 << " ) - ( " << c2 << " ) = " << c_ans << endl;
	}
	else if (Operation == 3)
	{
		int mul;
		cout << "Enter the complex number: ";
		cin >> c1;
		cout << "Enter a multiplier: ";
		cin >> mul;
		c_ans = c1 * mul;
		cout << "( " << c1 << " ) * ( " << mul << " ) = " << c_ans << endl;
	}

	cout << "Enter 0 to exit: ";
	cin >> repeat;
	cout << endl;
	} while(repeat);
	
	return 0;
}


void printMenu()
{
	cout << "1.Add  2. Sub  3. Scalar Multiply" << endl
		 << "Please enter the number to execute a operation: ";
}


Complex::Complex()						   	 				
{
	a = 0;
	b = 0;
}

Complex::Complex(int input_a, int input_b)	 
{
	a = input_a;
	b = input_b;
}

Complex Complex::operator + (Complex cmplx) 
{
	Complex c_ans(a, b);
	c_ans.a += cmplx.a;
	c_ans.b += cmplx.b;
	
	return c_ans;
}

Complex Complex::operator - (Complex cmplx)
{
	Complex c_ans(a, b);
	c_ans.a -= cmplx.a;
	c_ans.b -= cmplx.b;
	
	return c_ans;
}

Complex Complex::operator * (int mul)        
{
	Complex c_ans(a, b);
	c_ans.a *= mul;
	c_ans.b *= mul;
	
	return c_ans;
}

istream& operator >> (istream &Input, Complex &cmplx)
{
	char box[100];                
	char a[50], b[50];			  "
	int ix_box = 0, ix_ab = 0;    
	Input.getline(box,100);		  
	for(ix_box; isspace(box[ix_box]); ix_box++)
	{
	}
	
	a[ix_ab++] = box[ix_box++];			

	for(ix_box; isspace(box[ix_box]); ix_box++)
	{
	}

	for(ix_box; isdigit(box[ix_box]); ix_box++)	
	{
		a[ix_ab] = box[ix_box];
		ix_ab++;
	}
	a[ix_ab] = '\0';							
	cmplx.a = atoi(a);							 
	for(ix_box; !ispunct(box[ix_box]); ix_box++)
	{
	}

	ix_ab = 0;								
	b[ix_ab] = box[ix_box];	
	ix_ab++;
	ix_box++;
	
	for(ix_box; isspace(box[ix_box]); ix_box++)
	{
	}


	for(ix_box; isdigit(box[ix_box]); ix_box++)	 
	{
		b[ix_ab] = box[ix_box];
		ix_ab++;
	}
	b[ix_ab] = '\0';						 	 
	cmplx.b = atoi(b);						   	 
	
	return Input;
}

ostream& operator << (ostream &Output, Complex &cmplx)
{
	Output << cmplx.a;
	if(cmplx.b >= 0)
		Output << " + " << cmplx.b << "i";
	else
		Output << " - " << abs(cmplx.b) << "i"; 
	
	return Output;
} 
Last edited on
run the code too
operator >>

allows users to into cin >> objects
talking only about cin
cin has its own code embedded in to c++
im assuming if i want to cin objects

i have to make my own code to cin objects
and this is how i want my user to input
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