Common Operators in C

This guide covers the most frequently used operators in C, especially relevant for embedded systems programming. For a full reference, see: GeeksforGeeks: Operators in C

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1. Arithmetic Operators

Used for basic math operations.

int a = 10, b = 3;

int sum     = a + b;
int diff    = a - b;
int product = a * b;
int quotient= a / b;
int mod     = a % b;

Integer division truncates — 10 / 3 gives 3, not 3.33. Need to use double or float to avoid this!

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2. Relational Operators

Used to compare values — returns true or false. Better to use bool to make your intent clear, but we can use int too and it will return 1 or 0

bool equal      = (a == b);
bool not_equal  = (a != b);
bool greater    = (a > b);
bool less       = (a < b);
bool geq        = (a >= b);
bool leq        = (a <= b);

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3. Logical Operators

Used to combine or invert boolean expressions, works with ints or bools

Operator	Meaning	Example	Result (if a = true, b = false)
&&	Logical AND	a && b	false
\|\|	Logical OR	a \|\| b	true
!	Logical NOT	!a	false

Examples:

int a = 1, b = 0;
if (a && b) {
  // This won't run because b is false
}
if (a || b) {
  // This will run because a is true
}
if (!b) {
  // This will run because b is false
}

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4. Assignment Operators

Often we want to assign an updated value to a variable like x = x + 10. C has some special assignment operators which can be used to assign and update values, in one go. It saves on typing!

Operator	Meaning	Equivalent Expression
=	Assign	x = 5
+=	Add and assign	x = x + 2
-=	Subtract and assign	x = x - 1
*=	Multiply and assign	x = x * 3
/=	Divide and assign	x = x / 2
%=	Modulo and assign	x = x % 3

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5. Increment/Decrement

Used to step values up or down. We use these a lot in for loops

int i = 0;

i++;  // i = i + 1
i--;  // i = i - 1

for (int n =0; n < 10 ; n++) {
    // do stuff
}

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