[Term Entry] C Operators: Unary operators

content/c/concepts/operators/terms/unary-operators/unary-operators.md

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+---
+Title: 'Unary operators'
+Description: 'Perform operations on a single operand.'
+Subjects:
+  - 'Code Foundations'
+  - 'Computer Science'
+Tags:
+  - 'Arithmetic'
+  - 'Comparison'
+  - 'Logical'
+  - 'Operators'
+  - 'Unary'
+CatalogContent:
+  - 'learn-c'
+  - 'paths/computer-science'
+---
+
+**Unary operators** in C operate on a single operand to perform various operations such as incrementing, decrementing, negating, or manipulating bits. They are frequently used for modifying values, checking conditions, and optimizing calculations in expressions.
+
+## Syntax
+
+```pseudo
+operator operand;
+```
+
+- `operator`: A unary operator that performs an operation on a single operand.
+- `operand`: The variable or value on which the operator acts.
+
+> **Note:** In postfix notation, the operator is placed after the operand, and the original value is used before the operation takes effect.
+
+## Types of Unary operators
+
+### Increment (`++`)
+
+Increases the value of the operand by 1. Can be used in prefix (`++x`) or postfix (`x++`) notation.
+
+### Decrement (`--`)
+
+Decreases the value of the operand by 1. Can be used in prefix (`--x`) or postfix (`x--`) notation.
+
+### Unary Plus (`+`)
+
+Indicates a positive value. Rarely used explicitly, as numbers are positive by default.
+
+### Unary Minus (`-`)
+
+Negates the value of the operand.
+
+### Logical NOT (`!`)
+
+Reverses the truth value of the operand. If the operand is nonzero, it returns `0`; otherwise, it returns `1`.
+
+### Bitwise NOT (`~`)
+
+Inverts all bits of the operand.
+
+### Indirection (`*`)
+
+Accesses the value stored at a memory address (used with pointers).
+
+### Addressof (`&`)
+
+Retrieves the memory address of a variable.
+
+### Sizeof (`sizeof()`)
+
+Determines the size (in bytes) of a variable or data type.
+
+## Example
+
+In this example, various unary operators are demonstrated, such as negation, increment, decrement, bitwise operations, and the sizeof operator to show their effects on integer values:
+
+```c
+#include <stdio.h>
+
+int main() {
+  int a = 5;
+  int b = -a;    // Unary minus
+  int c = !a;    // Logical NOT
+  int d = ~a;    // Bitwise NOT
+  int e = ++a;   // Pre-increment
+  int f = a--;   // Post-decrement
+  int size = sizeof(a); // Sizeof operator
+
+  printf("Unary minus: %d\n", b);
+  printf("Logical NOT: %d\n", c);
+  printf("Bitwise NOT: %d\n", d);
+  printf("Pre-increment: %d\n", e);
+  printf("Post-decrement: %d\n", f);
+  printf("Sizeof operator: %d\n", size);
+
+  return 0;
+}
+```
+
+The code produces the output as:
+
+```shell
+Unary minus: -5
+Logical NOT: 0
+Bitwise NOT: -6
+Pre-increment: 6
+Post-decrement: 6
+Sizeof operator: 4
+```