Operators and expressions

Operators and Expressions in C

In C language, operators are special symbols used to perform operations on data and variables. An expression is a combination of operators and operands (variables/constants) that produces a result. Example: a + b is an expression where + is an operator and a, b are operands.

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1. Arithmetic Operators

These operators are used for mathematical calculations like addition, subtraction, multiplication, etc.

Operators: + (Addition), - (Subtraction), * (Multiplication), / (Division), % (Modulus)

#include <stdio.h>
int main() {
  int a = 10, b = 3;
  printf("a+b = %d\\n", a+b);
  printf("a-b = %d\\n", a-b);
  printf("a*b = %d\\n", a*b);
  printf("a/b = %d\\n", a/b);
  printf("a%%b = %d\\n", a%b);
  return 0;
}

Output:
a+b = 13
a-b = 7
a*b = 30
a/b = 3
a%b = 1

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2. Relational Operators

These operators are used to compare two values. The result is either true (1) or false (0).

Operators: == (equal to), != (not equal to), > (greater than), < (less than), >= (greater or equal), <= (less or equal)

#include <stdio.h>
int main() {
  int x = 5, y = 10;
  printf("x == y : %d\\n", x == y);
  printf("x != y : %d\\n", x != y);
  printf("x > y : %d\\n", x > y);
  printf("x < y : %d\\n", x < y);
  return 0;
}

Output:
x == y : 0
x != y : 1
x > y : 0
x < y : 1

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3. Logical Operators

Used to combine multiple conditions.

Operators: && (AND), || (OR), ! (NOT)

#include <stdio.h>
int main() {
  int a = 1, b = 0;
  printf("a && b = %d\\n", a && b);
  printf("a || b = %d\\n", a || b);
  printf("!a = %d\\n", !a);
  return 0;
}

Output:
a && b = 0
a || b = 1
!a = 0

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4. Bitwise Operators

Work on bits (0s and 1s) directly.

& (AND), | (OR), ^ (XOR), ~ (NOT), << (Left Shift), >> (Right Shift)

#include <stdio.h>
int main() {
  int a = 5, b = 3;
  printf("a & b = %d\\n", a & b);
  printf("a | b = %d\\n", a | b);
  printf("a ^ b = %d\\n", a ^ b);
  printf("~a = %d\\n", ~a);
  printf("a<<1 = %d\\n", a<<1);
  printf("a>>1 = %d\\n", a>>1);
  return 0;
}

Output:
a & b = 1
a | b = 7
a ^ b = 6
~a = -6
a<<1 = 10
a>>1 = 2

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5. Assignment Operators

Used to assign values to variables.

=, +=, -=, *=, /=, %=

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6. Increment / Decrement Operators

Increase or decrease a variable by 1.

++ (Increment), -- (Decrement)

Prefix: ++a → increment before use, Postfix: a++ → increment after use.

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7. Conditional (Ternary) Operator

Shortcut for if-else.

(condition) ? value_if_true : value_if_false

#include <stdio.h>
int main() {
  int x = 10, y = 20;
  int max = (x > y) ? x : y;
  printf("Max = %d", max);
  return 0;
}

Output:
Max = 20

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8. Operator Precedence and Associativity

When multiple operators appear in one expression, precedence decides which operator executes first, and associativity decides the order when operators have the same precedence.

Operators	Precedence	Associativity
() , [] , -> , .	Highest	Left to Right
++ , -- , ! , ~ , sizeof	High	Right to Left
* , / , %	Medium	Left to Right
+ , -	Medium	Left to Right
<< , >>	Low	Left to Right
< , > , <= , >=	Lower	Left to Right
== , !=	Lower	Left to Right
&	Very Low	Left to Right
^ , |	Very Low	Left to Right
&& , ||	Low	Left to Right
? :	Low	Right to Left
= , += , -=	Very Low	Right to Left
, (comma)	Lowest	Left to Right