Dev C++ Operator
C assignment Operator basics Assignment Operator is used to assign value to an variable. Assignment Operator is denoted by equal to (=) sign. This operator copies the value at the right side of the operator into the left side variable. The operand expr of a built-in prefix increment or decrement operator must be a modifiable (non-const) lvalue of non-boolean (since C17) arithmetic type or pointer to completely-defined object type.For non-boolean operands, the expression x is exactly equivalent to x + = 1, and the expression -x is exactly equivalent to x -= 1, that is, the prefix increment or decrement is an lvalue. Share code, track work, and ship software using integrated software delivery tools, hosted on premisis. Use all the Azure DevOps services or just the ones you need to complement your existing workflows. Note that the associativity is meaningful for member access operators, even though they are grouped with unary postfix operators: a. B is parsed (a. B) and not a. Operator precedence is unaffected by operator overloading.
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An operator is a symbol that tells the compiler to perform specific mathematical or logical functions. C language is rich in built-in operators and provides the following types of operators −
- Arithmetic Operators
- Relational Operators
- Logical Operators
- Bitwise Operators
- Assignment Operators
- Misc Operators
We will, in this chapter, look into the way each operator works. /http-wwwltotalcom-2007-11-how-to-displaly-line-number-in-dev-chtml-m-1.html.
Arithmetic Operators
The following table shows all the arithmetic operators supported by the C language. Assume variable A holds 10 and variable B holds 20 then −
Operator | Description | Example |
---|---|---|
+ | Adds two operands. | A + B = 30 |
− | Subtracts second operand from the first. | A − B = -10 |
* | Multiplies both operands. | A * B = 200 |
/ | Divides numerator by de-numerator. | B / A = 2 |
% | Modulus Operator and remainder of after an integer division. | B % A = 0 |
++ | Increment operator increases the integer value by one. | A++ = 11 |
-- | Decrement operator decreases the integer value by one. | A-- = 9 |
Relational Operators
The following table shows all the relational operators supported by C. Assume variable A holds 10 and variable B holds 20 then −
Operator | Description | Example |
---|---|---|
Checks if the values of two operands are equal or not. If yes, then the condition becomes true. | (A B) is not true. | |
!= | Checks if the values of two operands are equal or not. If the values are not equal, then the condition becomes true. | (A != B) is true. |
> | Checks if the value of left operand is greater than the value of right operand. If yes, then the condition becomes true. | (A > B) is not true. |
< | Checks if the value of left operand is less than the value of right operand. If yes, then the condition becomes true. | (A < B) is true. |
>= | Checks if the value of left operand is greater than or equal to the value of right operand. If yes, then the condition becomes true. | (A >= B) is not true. |
<= | Checks if the value of left operand is less than or equal to the value of right operand. If yes, then the condition becomes true. | (A <= B) is true. |
Logical Operators
Following table shows all the logical operators supported by C language. Assume variable A holds 1 and variable B holds 0, then −
Operator | Description | Example |
---|---|---|
&& | Called Logical AND operator. If both the operands are non-zero, then the condition becomes true. | (A && B) is false. |
Called Logical OR Operator. If any of the two operands is non-zero, then the condition becomes true. | (A B) is true. | |
! | Called Logical NOT Operator. It is used to reverse the logical state of its operand. If a condition is true, then Logical NOT operator will make it false. | !(A && B) is true. |
Bitwise Operators
Bitwise operator works on bits and perform bit-by-bit operation. The truth tables for &, , and ^ is as follows −
p | q | p & q | p q | p ^ q |
---|---|---|---|---|
0 | 0 | 0 | 0 | 0 |
0 | 1 | 0 | 1 | 1 |
1 | 1 | 1 | 1 | 0 |
1 | 0 | 0 | 1 | 1 |
Assume A = 60 and B = 13 in binary format, they will be as follows −
A = 0011 1100
B = 0000 1101
-----------------
A&B = 0000 1100
A B = 0011 1101
/auto-tune-tyrone-gta-rp.html. A^B = 0011 0001
~A = 1100 0011
The following table lists the bitwise operators supported by C. Assume variable 'A' holds 60 and variable 'B' holds 13, then −
Operator | Description | Example |
---|---|---|
& | Binary AND Operator copies a bit to the result if it exists in both operands. | (A & B) = 12, i.e., 0000 1100 |
Binary OR Operator copies a bit if it exists in either operand. | (A B) = 61, i.e., 0011 1101 | |
^ | Binary XOR Operator copies the bit if it is set in one operand but not both. | (A ^ B) = 49, i.e., 0011 0001 |
~ | Binary One's Complement Operator is unary and has the effect of 'flipping' bits. | (~A ) = ~(60), i.e,. -0111101 |
<< | Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. | A << 2 = 240 i.e., 1111 0000 |
>> | Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. | A >> 2 = 15 i.e., 0000 1111 |
Assignment Operators
The following table lists the assignment operators supported by the C language −
Operator | Description | Example |
---|---|---|
= | Simple assignment operator. Assigns values from right side operands to left side operand | C = A + B will assign the value of A + B to C |
+= | Add AND assignment operator. It adds the right operand to the left operand and assign the result to the left operand. | C += A is equivalent to C = C + A |
-= | Subtract AND assignment operator. It subtracts the right operand from the left operand and assigns the result to the left operand. | C -= A is equivalent to C = C - A |
*= | Multiply AND assignment operator. It multiplies the right operand with the left operand and assigns the result to the left operand. | C *= A is equivalent to C = C * A |
/= | Divide AND assignment operator. It divides the left operand with the right operand and assigns the result to the left operand. | C /= A is equivalent to C = C / A |
%= | Modulus AND assignment operator. It takes modulus using two operands and assigns the result to the left operand. | C %= A is equivalent to C = C % A |
<<= | Left shift AND assignment operator. | C <<= 2 is same as C = C << 2 |
>>= | Right shift AND assignment operator. | C >>= 2 is same as C = C >> 2 |
&= | Bitwise AND assignment operator. | C &= 2 is same as C = C & 2 |
^= | Bitwise exclusive OR and assignment operator. | C ^= 2 is same as C = C ^ 2 |
= | Bitwise inclusive OR and assignment operator. | C = 2 is same as C = C 2 |
Misc Operators ↦ sizeof & ternary
Besides the operators discussed above, there are a few other important operators including sizeof and ? : supported by the C Language.
Operator | Description | Example |
---|---|---|
sizeof() | Returns the size of a variable. | sizeof(a), where a is integer, will return 4. |
& | Returns the address of a variable. | &a; returns the actual address of the variable. |
* | Pointer to a variable. | *a; |
? : | Conditional Expression. | If Condition is true ? then value X : otherwise value Y |
Operators Precedence in C
Operator precedence determines the grouping of terms in an expression and decides how an expression is evaluated. Certain operators have higher precedence than others; for example, the multiplication operator has a higher precedence than the addition operator.
For example, x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has a higher precedence than +, so it first gets multiplied with 3*2 and then adds into 7.
Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedence operators will be evaluated first.
Category | Operator | Associativity |
---|---|---|
Postfix | () [] -> . ++ - - | Left to right |
Unary | + - ! ~ ++ - - (type)* & sizeof | Right to left |
Multiplicative | * / % | Left to right |
Additive | + - | Left to right |
Shift | << >> | Left to right |
Relational | < <= > >= | Left to right |
Equality | != | Left to right |
Bitwise AND | & | Left to right |
Bitwise XOR | ^ | Left to right |
Bitwise OR | Left to right | |
Logical AND | && | Left to right |
Logical OR | Left to right | |
Conditional | ?: | Right to left |
Assignment | = += -= *= /= %=>>= <<= &= ^= = | Right to left |
Comma | , | Left to right |
Assignment operator (=)
The assignment operator assigns a value to a variable.This statement assigns the integer value
5
to the variable x
. The assignment operation always takes place from right to left, and never the other way around:This statement assigns to variable
x
the value contained in variable y
. The value of x
at the moment this statement is executed is lost and replaced by the value of y
.Consider also that we are only assigning the value of
y
to x
at the moment of the assignment operation. Therefore, if y
changes at a later moment, it will not affect the new value taken by x
.For example, let's have a look at the following code - I have included the evolution of the content stored in the variables as comments:
This program prints on screen the final values of
a
and b
(4 and 7, respectively). Notice how a
was not affected by the final modification of b
, even though we declared a = b
earlier.Assignment operations are expressions that can be evaluated. That means that the assignment itself has a value, and -for fundamental types- this value is the one assigned in the operation. For example:
In this expression,
y
is assigned the result of adding 2 and the value of another assignment expression (which has itself a value of 5). It is roughly equivalent to:With the final result of assigning 7 to
y
.The following expression is also valid in C++:
It assigns 5 to the all three variables:
x
, y
and z
; always from right-to-left.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. For example:results in variable
x
containing the value 2, since dividing 11 by 3 results in 3, with a remainder of 2.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:expression | equivalent to.. |
---|---|
y += x; | y = y + x; |
x -= 5; | x = x - 5; |
x /= y; | x = x / y; |
price *= units + 1; | price = price * (units+1); |
and the same for all other compound assignment operators. For example:
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. Thus:are all equivalent in its functionality; the three of them increase by one the value of
x
.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. Notice the difference:Example 1 | Example 2 |
---|---|
x = 3; | x = 3; |
In Example 1, the value assigned to
y
is the value of x
after being increased. While in Example 2, it is the value x
had before being increased.Relational and comparison operators ( , !=, >, <, >=, <= )
Two expressions can be compared using relational and equality operators. For example, to know if two values are equal or if one is greater than the other.The result of such an operation is either true or false (i.e., a Boolean value).
The relational operators in C++ are:
operator | description |
---|---|
Equal to | |
!= | Not equal to |
< | Less than |
> | Greater than |
<= | Less than or equal to |
>= | Greater than or equal to |
Here there are some examples:
Of course, it's not just numeric constants that can be compared, but just any value, including, of course, variables. Suppose that
a=2
, b=3
and c=6
, then:Be careful! The assignment operator (operator
=
, with one equal sign) is not the same as the equality comparison operator (operator , with two equal signs); the first one (=
) assigns the value on the right-hand to the variable on its left, while the other () compares whether the values on both sides of the operator are equal. Therefore, in the last expression ((b=2) a
), we first assigned the value 2
to b
and then we compared it to a
(that also stores the value 2), yielding true
.Logical operators ( !, &&, )
The operator!
is the C++ operator for the Boolean operation NOT. It has only one operand, to its right, and inverts it, producing false
if its operand is true
, and true
if its operand is false
. Basically, it returns the opposite Boolean value of evaluating its operand. For example:Dev C++ No Match For Operator
The logical operators&&
and
are used when evaluating two expressions to obtain a single relational result. The operator &&
corresponds to the Boolean logical operation AND, which yields true
if both its operands are true
, and false
otherwise. The following panel shows the result of operator &&
evaluating the expression a&&b
:&& OPERATOR (and) | ||
---|---|---|
a | b | a && b |
true | true | true |
true | false | false |
false | true | false |
false | false | false |
The operator
corresponds to the Boolean logical operation OR, which yields true
if either of its operands is true
, thus being false only when both operands are false. Here are the possible results of a b
:OPERATOR (or) | ||
---|---|---|
a | b | a b |
true | true | true |
true | false | true |
false | true | true |
false | false | false |
For example:
When using the logical operators, C++ only evaluates what is necessary from left to right to come up with the combined relational result, ignoring the rest. Therefore, in the last example (
(55) (3>6)
), C++ evaluates first whether 55
is true
, and if so, it never checks whether 3>6
is true
or not. This is known as short-circuit evaluation, and works like this for these operators:operator | short-circuit |
---|---|
&& | if the left-hand side expression is false , the combined result is false (the right-hand side expression is never evaluated). |
| if the left-hand side expression is true , the combined result is true (the right-hand side expression is never evaluated). |
This is mostly important when the right-hand expression has side effects, such as altering values:
Here, the combined conditional expression would increase
i
by one, but only if the condition on the left of &&
is true
, because otherwise, the condition on the right-hand side (++i<n
) is never evaluated.Conditional ternary operator ( ? )
The conditional operator evaluates an expression, returning one value if that expression evaluates totrue
, 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
.For example:
In this example,
a
was 2, and b
was 7, so the expression being evaluated (a>b
) was not true
, thus the first value specified after the question mark was discarded in favor of the second value (the one after the colon) which was b
(with a value of 7).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.For example, the following code:
would first assign the value 3 to
b
, and then assign b+2
to variable a
. So, at the end, variable a
would contain the value 5 while variable b
would contain value 3.Bitwise operators ( &, , ^, ~, <<, >> )
Bitwise operators modify variables considering the bit patterns that represent the values they store.operator | asm equivalent | description |
---|---|---|
& | AND | Bitwise AND |
| OR | Bitwise inclusive OR |
^ | XOR | Bitwise exclusive OR |
~ | NOT | Unary complement (bit inversion) |
<< | SHL | Shift bits left |
>> | SHR | Shift bits right |
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 (()):The previous code converts the floating-point number
3.14
to an integer value (3
); the remainder is lost. Here, the typecasting operator was (int)
. Another way to do the same thing in C++ is to use the functional notation preceding the expression to be converted by the type and enclosing the expression between parentheses:Both ways of casting types are valid in C++.
sizeof
This operator accepts one parameter, which can be either a type or a variable, and returns the size in bytes of that type or object:Here,
x
is assigned the value 1
, because char
is a type with a size of one byte.The value returned by
sizeof
is a compile-time constant, so it is always determined before program execution.Other operators
Later in these tutorials, we will see a few more operators, like the ones referring to pointers or the specifics for object-oriented programming.Precedence of operators
A single expression may have multiple operators. For example:In C++, the above expression always assigns 6 to variable
x
, because the %
operator has a higher precedence than the Dev C++ Online
+
operator, and is always evaluated before. Parts of the expressions can be enclosed in parenthesis to override this precedence order, or to make explicitly clear the intended effect. Notice the difference:From greatest to smallest priority, C++ operators are evaluated in the following order:
Level | Precedence group | Operator | Description | Grouping |
---|---|---|---|---|
1 | Scope | :: | scope qualifier | Left-to-right |
2 | Postfix (unary) | ++ -- | postfix increment / decrement | Left-to-right |
() | functional forms | |||
[] | subscript | |||
. -> | member access | |||
3 | Prefix (unary) | ++ -- | prefix increment / decrement | Right-to-left |
~ ! | bitwise NOT / logical NOT | |||
+ - | unary prefix | |||
& * | reference / dereference | |||
new delete | allocation / deallocation | |||
sizeof | parameter pack | |||
(type) | C-style type-casting | |||
4 | Pointer-to-member | .* ->* | access pointer | Left-to-right |
5 | Arithmetic: scaling | * / % | multiply, divide, modulo | Left-to-right |
6 | Arithmetic: addition | + - | addition, subtraction | Left-to-right |
7 | Bitwise shift | << >> | shift left, shift right | Left-to-right |
8 | Relational | < > <= >= | comparison operators | Left-to-right |
9 | Equality | != | equality / inequality | Left-to-right |
10 | And | & | bitwise AND | Left-to-right |
11 | Exclusive or | ^ | bitwise XOR | Left-to-right |
12 | Inclusive or |
| bitwise OR | Left-to-right |
13 | Conjunction | && | logical AND | Left-to-right |
14 | Disjunction |
| logical OR | Left-to-right |
15 | Assignment-level expressions | = *= /= %= += -= | assignment / compound assignment | Right-to-left |
?: | conditional operator | |||
16 | Sequencing | , | comma separator | Left-to-right |
When an expression has two operators with the same precedence level, grouping determines which one is evaluated first: either left-to-right or right-to-left.
Dev C Operator Jobs
C++ What Is Operator
Enclosing all sub-statements in parentheses (even those unnecessary because of their precedence) improves code readability.Previous: Constants | Index | Next: Basic Input/Output |