C operator

Introduction to C operators and operator precedence

C provides us with a variety of operators that can be used to perform operations on data.

In particular, we can identify different types of operators:

Arithmetic Operator
Comparison operator
Logical Operators
Compound assignment operator
Bitwise operator
pointerOperators
Structure operator
Miscellaneous operators

In this blog post, I will use 2 fictitious variables to detail all these variablesawithbas an example.

I will exclude bitwise operators, structural operators, and pointer operators from this list, because I will write a specific blog post specifically for them.

Arithmetic Operator

In this macro group, I will separate binary operators and unary operators.

Binary operators use two operands to work:

operator	Name	example
`=`	task	`a = b`
`+`	Add to	`a + b`
`-`	Subtraction	`a - b`
`*`	multiplication	`a * b`
`/`	distribution	`a / b`
`%`	Modulus	`a % b`

Unary operators can only use one operand:

operator	Name	example
`+`	One dollar plus	`+a`
`-`	One yuan minus	`-a`
`++`	Increment	`a++`or`++a`
`--`	Decrease	`a--`or`--a`

The difference betweena++with++athat's ita++increaseaVariables after use.++aincreaseaVariable before using it.

E.g:

int a = 2;
int b;
b = a++ /* b is 2, a is 3 */
b = ++a /* b is 4, a is 4 */

The same goes for the decrement operator.

Comparison operator

operator	Name	example
`==`	Equality operator	`a == b`
`!=`	Not equal to operator	`a != b`
`>`	more than the	`a > b`
`<`	less than	`a < b`
`>=`	greater than or equal to	`a >= b`
`<=`	less than or equal to	`a <= b`

Logical Operators

!No (example:!a)
&&AND (for example:a && b)
||Or (for example:a || b)

These operators are very useful when using boolean values.

Compound assignment operator

These operators are very useful for performing assignments and performing arithmetic operations at the same time:

operator	Name	example
`+=`	Additive distribution	`a += b`
`-=`	Subtractive distribution	`a -= b`
`*=`	Multiplicative distribution	`a *= b`
`/=`	Department allocation	`a /= b`
`%=`	Mode distribution	`a %= b`

Miscellaneous operators

Ternary operator

The ternary operator isCYou can use 3 operands, which is a short way to express conditions.

It looks like this:

<condition> ? <expression> : <expression>

example:

a ? b : c

in caseaIs evaluated astrue,thenbThe statement has been executed, otherwisecYes.

The function of the ternary operator is the same as the if/else condition, except that it has a shorter representation time and can be inlined into the expression.

size

ThissizeofThe operator returns the size of the operand you pass. You can pass variables and even types.

Example usage:

#include <stdio.h>

int main(void) {
  int age = 37;
  printf("%ld\n", sizeof(age));
  printf("%ld", sizeof(int));
}

Operator precedence

For all these operators (and more operators that I haven't covered in this article, including bitwise operators, structural operators, and pointer operators), you must be careful when using them together in a single expression.

Suppose we have this operation:

int a = 2;
int b = 4;
int c = b + a * a / b - a;

What's the valuec? Do we perform addition before addition and division?

There is a set of rules that can help us solve this problem.

In order to go from low priority to high priority, we have:

This=Assignment operator
This+with- BinaryOperators
This*with/Operators
This+with-Unary operator

Operators also have association rules, except for unary operators and assignments, the rules are always from left to right.

in:

int c = b + a * a / b - a;

We execute firsta * a / b, Since it is from left to right, we can divide it intoa * aAnd result/ b:2 * 2 = 4,4 / 4 = 1.

Then we can add and subtract: 4 +1-2.cYes3.

However, in all cases, I want to make sure that you realize that you can use parentheses to make any similar expression easier to read and understand.

Parentheses have a higher priority than anything else.

The above example expression can be rewritten as:

int c = b + ((a * a) / b) - a;

And we don’t have to think too much.

Download mine for freeC manual