Arithmetic Operations and Expressions

1. In an arithmetic expression, the type of the value produced and the value of the result can depend on the type of the data involved
   
   
2. In any assignment statement
   Variable = Expression
   involving an expression, the expression is first evaluated and then the result is assigned to the variable on the left
   
   
3. Example:
   
   int integer1 = 11, integer2 = 4, integer3;
   double double1= 11.0, double2 = 4.0, double3;
   integer3 = integer1 / integer2; // integer3 has the value of 2
   integer4 = integer1 % integer2; // integer4 is 3
   double3 = integer1 / integer2; // double3 has the value of 2.00
   double3 = double1 / double2; // double3 has the value of 2.75
   
   
4. The quotient of 2 integers is given by the integer obtained from the result by dropping the fractional part (not rounding). The remainder. if any, can be retrieved using the % operator, which is defined for integer operation only.
   
   
5. In an arithmetic operation involving an integer and a double, the integer is first converted to a double, and the operation is carried out and the result is a double value
   
   
6. Results of operations using / and % with negative integers can differ depending on the compiler, and therefore should be avoided
   
   
7. An expression that has more than one operator can have the order of operation changed by proper use of parentheses
   For example, the following 2 expressions give different results
   (x + y) * z;
   x + (y * z);
   
   
8. In the absence of parentheses, the computer follows the so-called precedence rules to determine the actual order of operations.
   • High precedence operators must be carried out first.
   • Operators having the same level of precedence are evaluated from left to right
   • A complete set C++ precedence rules are given in Appendix 2. Operators are listed from high to low precedence. Operator having the same level of precedence are grouped together.
     
   • For example, you will find the following operators list:
     
     !   not
     ------------------------------
     -   unary minus
     +   unary plus
     ------------------------------
     *   multiplication
     /   division
     %   integer remainder (modulo)
     ------------------------------
     +   addition
     -   subtraction
     ------------------------------
     =   assignment
     
     
   • Use parentheses if you have any doubt about the precedence of the operators
     
     
   • The use of parentheses also helps to improve the readability of the expression
     
     
9. C++ has a shorthand notation of the general form:
   
   Variable Operator = Expression
   
   which is defined to be equivalent to
   
   Variable = Variable Operation (Expression)
   
   Examples:
   count += 2;                                // count = count + 2;
   cost -= discount;                       // cost = cost - discount;
   position += velocity * time;     // position = position + velocity * time;
   change %= 100;                        // change = change % 100;
   
   
10. One must be careful when writing expressions from mathematical formulas