Friday, April 26, 2019

Understanding Operators In C++ Language

Once introduced to variables and constants, we can begin to operate with them by using operators. What follows is a complete list of operators. At this point, it is likely not necessary to know all of them, but they are all listed here to also serve as reference.

Assignment operator (=)

The assignment operator assigns a value to a variable.

Consider also that we are only assigning the value of y to x at the moment of the assignment operation. Therefore, if ychanges at a later moment, it will not affect the new value taken by x.

Arithmetic operators ( +, -, *, /, % )

The five arithmetical operations supported by C++ are: 

operator    description

+                addition
-               subtraction
*             multiplication
/                 division
%               modulo

Operations of addition, subtraction, multiplication and division correspond literally to their respective mathematical operators. The last one, modulo operator, represented by a percentage sign (%), gives the remainder of a division of two values.

Compound assignment (+=, -=, *=, /=, %=, >>=, <<=, &=, ^=, |=)

Compound assignment operators modify the current value of a variable by performing an operation on it. They are equivalent to assigning the result of an operation to the first operand

Increment and decrement (++, --)

Some expression can be shortened even more: the increase operator (++) and the decrease operator (--) increase or reduce by one the value stored in a variable. They are equivalent to +=1 and to -=1, respectively. 

In the early C compilers, the three previous expressions may have produced different executable code depending on which one was used. Nowadays, this type of code optimization is generally performed automatically by the compiler, thus the three expressions should produce exactly the same executable code.

A peculiarity of this operator is that it can be used both as a prefix and as a suffix. That means that it can be written either before the variable name (++x) or after it (x++). Although in simple expressions like x++ or ++x, both have exactly the same meaning; in other expressions in which the result of the increment or decrement operation is evaluated, they may have an important difference in their meaning: In the case that the increase operator is used as a prefix (++x) of the value, the expression evaluates to the final value of x, once it is already increased. On the other hand, in case that it is used as a suffix (x++), the value is also increased, but the expression evaluates to the value that x had before being increased. 

Conditional ternary operator ( ? )

The conditional operator evaluates an expression, returning one value if that expression evaluates to true, and a different one if the expression evaluates as false. Its syntax is:

condition ? result1 : result2

If condition is true, the entire expression evaluates to result1, and otherwise to result2.

Comma operator ( , )

The comma operator (,) is used to separate two or more expressions that are included where only one expression is expected. When the set of expressions has to be evaluated for a value, only the right-most expression is considered.

Explicit type casting operator

Type casting operators allow to convert a value of a given type to another type. There are several ways to do this in C++. The simplest one, which has been inherited from the C language, is to precede the expression to be converted by the new type enclosed between parentheses (()):