NOT for inverting bits in Embedded C - Step-by-Step Execution

Concept Flow - NOT for inverting bits

Start with a number

↓

Apply NOT (~) operator

↓

Each bit flips: 0->1, 1->0

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Result is bitwise inverted number

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Use or store the result

↓

End

The NOT operator (~) flips every bit of a number, turning 0s into 1s and 1s into 0s, producing the bitwise inverse.

Execution Sample

Embedded C

unsigned char x = 0b10101010;
unsigned char y = ~x;
// y now holds 0b01010101

This code flips all bits of x using ~, storing the inverted bits in y.

Execution Table

Step	Variable	Value (binary)	Action	Result (binary)
1	x	10101010	Initial value	10101010
2	y	N/A	Apply ~ to x	01010101
3	y	01010101	Store inverted bits in y	01010101

💡 All bits of x are flipped by ~, producing y with inverted bits.

Variable Tracker

Variable	Start	After NOT (~)	Final
x	10101010	10101010	10101010
y	N/A	01010101	01010101

Key Moments - 3 Insights

Why does applying ~ to 0b10101010 produce 0b01010101?

Because ~ flips each bit: every 1 becomes 0 and every 0 becomes 1, as shown in execution_table step 2.

Does ~ change the original variable x?

No, ~ creates a new inverted value; x remains unchanged as shown in variable_tracker.

Why is the result stored in a new variable y?

Because ~ returns a new value; to keep the inverted bits, you must assign it to a variable like y.

Visual Quiz - 3 Questions

Look at the execution_table at step 2, what is the binary value of y after applying ~ to x?

A 01010101

B 10101010

C 11111111

D 00000000

💡 Hint

Check the 'Result (binary)' column in execution_table row for step 2.

At which step does the variable y get its value assigned?

A Step 1

B Step 2

C Step 3

D No assignment

💡 Hint

Look at the 'Action' column in execution_table where y is stored.

If x was 0b11110000, what would y be after applying ~?

A 11110000

B 00001111

C 00000000

D 11111111

💡 Hint

Remember ~ flips each bit; see variable_tracker for how bits invert.

Concept Snapshot

Use ~ operator to invert bits of a number.
Each 0 bit becomes 1, each 1 bit becomes 0.
Original variable stays unchanged.
Assign result to new variable to keep inverted bits.
Example: ~0b10101010 = 0b01010101.

Full Transcript

This visual trace shows how the NOT operator (~) in embedded C flips bits of a number. Starting with x = 0b10101010, applying ~ creates a new value y = 0b01010101 where every bit is inverted. The original x remains the same. The execution table walks through each step: initial value, applying ~, and storing the result. The variable tracker shows how x stays constant while y changes. Common confusions include understanding that ~ flips bits, does not change the original variable, and requires assignment to store the result. The quiz questions reinforce these points by asking about values at specific steps and what happens if input changes.