Signed vs unsigned behavior on 8-bit MCU in Embedded C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an 8-bit unsigned variable.

Embedded C

unsigned char [1] = 255;

Drag options to blanks, or click blank then click option'

Anum

Bvalue

Ccount

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using a signed type instead of unsigned.

Choosing a variable name that is not descriptive.

We declare an 8-bit unsigned variable named num to hold values from 0 to 255.

2fill in blank

medium

Complete the code to assign a negative value to a signed 8-bit variable.

Embedded C

signed char [1] = -128;

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Adata

Btemp

Cval

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Using unsigned char for negative values.

Assigning values outside the range -128 to 127.

The variable temp is declared as signed char to hold negative values down to -128.

3fill in blank

hard

Fix the error in the code to correctly add two unsigned 8-bit variables without overflow.

Embedded C

unsigned char a = 200;
unsigned char b = 100;
unsigned int sum = a [1] b;

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A-

B*

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

Storing the result in an 8-bit variable causing overflow.

Use the + operator to add the two unsigned variables. The sum is stored in a wider type to avoid overflow.

4fill in blank

hard

Fill in the blank to correctly check if a signed 8-bit variable is negative.

Embedded C

signed char x = -5;
if (x [1] 0) {
    // x is negative
}

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A!=

B>

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using > instead of < for negative check.

Using wrong operators like == or !=.

Use < to check if x is less than zero.

5fill in blank

hard

Fill all three blanks to create a loop that counts down an unsigned 8-bit variable from 10 to 0.

Embedded C

unsigned char i = [1];
while (i [2] 0) {
    // do something
    i [3] 1;
}

Drag options to blanks, or click blank then click option'

A10

B>

C-=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > in the loop condition.

Using ++ instead of -= to decrement.

Initialize i to 10, loop while i > 0, and decrement i by 1 each time using -=.