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  1. //DISPLAY 11.8 Overloading << and >>
  2. //Program to demonstrate the class Money.
  3. #include <iostream>
  4. #include <fstream>
  5. #include <cstdlib>
  6. #include <cctype>
  7. using namespace std;
  8.  
  9. //Class for amounts of money in U.S. currency.
  10. class Money
  11. {
  12. public:
  13.     friend Money operator +(const Money& amount1, const Money& amount2);
  14.  
  15.     friend Money operator -(const Money& amount1, const Money& amount2);
  16.  
  17.     friend Money operator -(const Money& amount);
  18.  
  19.     friend bool operator ==(const Money& amount1, const Money& amount2);
  20.  
  21.     friend bool operator < (const Money& amount1, const Money& amount2);
  22.     //Returns true if amount1 is less than amount2; false otherwise.
  23.  
  24.  
  25.     Money(long dollars, int cents);
  26.  
  27.     Money(long dollars);
  28.  
  29.     Money( );
  30.  
  31.     double get_value( ) const;
  32.  
  33.     friend istream& operator >>(istream& ins, Money& amount);
  34.     //Overloads the >> operator so it can be used to input values of type Money.
  35.     //Notation for inputting negative amounts is as in -$100.00.
  36.     //Precondition: If ins is a file input stream, then ins has already been
  37.     //connected to a file.
  38.  
  39.     friend ostream& operator <<(ostream& outs, const Money& amount);
  40.     //Overloads the << operator so it can be used to output values of type Money.
  41.     //Precedes each output value of type Money with a dollar sign.
  42.     //Precondition: If outs is a file output stream,
  43.     //then outs has already been connected to a file.
  44. private:
  45.     long all_cents;
  46. };
  47. int digit_to_int(char c);
  48. //Used in the definition of the overloaded input operator >>.
  49. //Precondition: c is one of the digits '0' through '9'.
  50. //Returns the integer for the digit; for example, digit_to_int('3') returns 3.
  51.  
  52. int main( )
  53. {
  54.     Money amount1, amount2;
  55.  
  56.     cout << "input first amount:";
  57.     cin >> amount1;
  58.     cout << "input second amount:";
  59.     cin >> amount2;
  60.  
  61.     cout << "You entered " << amount1 << " and " << amount2 << endl;
  62.     cout << "Negated " << -amount1 << " and " << -amount2 << endl;
  63.     cout << "Sum " << amount1 + amount2 << endl;
  64.     cout << "Difference " << amount1 - amount2 << endl;
  65.  
  66.     if (amount1 < amount2) {
  67.         cout << amount1 << " < " << amount2;
  68.     } else if (amount2 < amount1) {
  69.         cout << amount1 << " > " << amount2;
  70.     } else {
  71.         cout << amount1 << " = " << amount2;
  72.     }
  73.     cout << endl;
  74.  
  75.     return 0;
  76. }
  77.  
  78. Money operator +(const Money& amount1, const Money& amount2)
  79. {
  80.     Money temp;
  81.     temp.all_cents = amount1.all_cents + amount2.all_cents;
  82.     return temp;
  83. }
  84.  
  85. bool operator ==(const Money& amount1, const Money& amount2)
  86. {
  87.     return (amount1.all_cents == amount2.all_cents);
  88. }
  89.  
  90. Money operator -(const Money& amount1, const Money& amount2)
  91. {
  92.     Money temp;
  93.     temp.all_cents = amount1.all_cents - amount2.all_cents;
  94.     return temp;
  95. }
  96.  
  97. Money operator -(const Money& amount)
  98. {
  99.     Money temp;
  100.     temp.all_cents = -amount.all_cents;
  101.     return temp;
  102. }
  103.  
  104. bool operator < (const Money& amount1, const Money& amount2){
  105.     return amount1.all_cents < amount2.all_cents;
  106. }
  107.  
  108. //Uses iostream, cctype, cstdlib:
  109. istream& operator >>(istream& ins, Money& amount)
  110. {
  111.     char one_char, decimal_point,
  112.          digit1, digit2; //digits for the amount of cents
  113.     long dollars;
  114.     int cents;
  115.     bool negative;//set to true if input is negative.
  116.  
  117.     ins >> one_char;
  118.     if (one_char == '-')
  119.     {
  120.         negative = true;
  121.         ins >> one_char; //read '$'
  122.     }
  123.     else
  124.         negative = false;
  125.     //if input is legal, then one_char == '$'
  126.  
  127.     ins >> dollars >> decimal_point >> digit1 >> digit2;
  128.  
  129.     if ( one_char != '$' || decimal_point != '.'
  130.             || !isdigit(digit1) || !isdigit(digit2) )
  131.     {
  132.         cout << "Error illegal form for money input\n";
  133.         exit(1);
  134.     }
  135.  
  136.     cents = digit_to_int(digit1)*10 + digit_to_int(digit2);
  137.  
  138.     amount.all_cents = dollars*100 + cents;
  139.     if (negative)
  140.         amount.all_cents = -amount.all_cents;
  141.  
  142.  
  143.     return ins;
  144. }
  145.  
  146. int digit_to_int(char c)
  147. {
  148.     return ( static_cast<int>(c) - static_cast<int>('0') );
  149. }
  150.  
  151. //Uses cstdlib and iostream:
  152. ostream& operator <<(ostream& outs, const Money& amount)
  153. {
  154.     long positive_cents, dollars, cents;
  155.     positive_cents = labs(amount.all_cents);
  156.     dollars = positive_cents/100;
  157.     cents = positive_cents%100;
  158.  
  159.     if (amount.all_cents < 0)
  160.         outs << "-$" << dollars << '.';
  161.     else
  162.         outs << "$" << dollars << '.';
  163.  
  164.     if (cents < 10)
  165.         outs << '0';
  166.     outs << cents;
  167.  
  168.     return outs;
  169. }
  170.  
  171. Money::Money(long dollars, int cents)
  172. {
  173.     if(dollars*cents < 0) //If one is negative and one is positive
  174.  
  175.  
  176.     {
  177.         cout << "Illegal values for dollars and cents.\n";
  178.         exit(1);
  179.     }
  180.     all_cents = dollars*100 + cents;
  181. }
  182.  
  183. Money::Money(long dollars) : all_cents(dollars*100)
  184. {
  185.     //Body intentionally blank.
  186. }
  187.  
  188. Money::Money( ) : all_cents(0)
  189. {
  190.     //Body intentionally blank.
  191. }
  192.  
Success #stdin #stdout 0s 3420KB
comments (?)
stdin
copy 
$12.54
$10.44
stdout
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input first amount:input second amount:You entered $12.54 and $10.44
Negated -$12.54 and -$10.44
Sum $22.98
Difference $2.10
$12.54 > $10.44
https://ideone.com/CLg0ST
language:
C++14 (clang 8.0)
created:
8 years ago
visibility:
public

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