Regarding known issues, we’ve made some fixes for high, constant CPU use in random extensions or tabs, but since there could be many possible causes, we’re still very interested in knowing places where people are still seeing it, especially if it can be consistently reproduced. We’ve also got a discussion going for. Feb 19, 2020  Outside of technical know-how, employers are increasingly looking for developers with strong soft skills. 'These little things can be the differentiator along.

Mar 05, 2020  Created by Alex Garland. With Sonoya Mizuno, Nick Offerman, Jin Ha, Zach Grenier. A computer engineer investigates the secretive development division in her company, which she believes is behind the disappearance of her boyfriend. In schools and colleges the most commonly used compiler is Turbo C. Most of the programs written in this book are compatible with Turbo C. It is better to use Visual C because advanced features like namespaces and exception handling are not available in older versions of Turbo C. All compilers will support the basic features of C. Almost all the files under /dev are device files.Whereas reading and writing to a regular file stores data on a disk or other filesystem, accessing a device file communicates with a driver in the kernel, which generally in turn communicates with a piece of hardware (a hardware device, hence the name).

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.
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; y = ++x; // x contains 4, y contains 4	x = 3; y = x++; // x contains 4, y contains 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:

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 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.
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 + 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.
Enclosing all sub-statements in parentheses (even those unnecessary because of their precedence) improves code readability.

Previous: Constants

Index

Next: Basic Input/Output

• C Programming Tutorial
• C Programming useful Resources

• Selected Reading

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.

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

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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 −

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A = 0011 1100

B = 0000 1101

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A&B = 0000 1100

A B = 0011 1101

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

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Besides the operators discussed above, there are a few other important operators including sizeof and ? : supported by the C Language.

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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

What Is Known Devs In C Language

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