Endianness (big-endian vs little-endian) in Embedded C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a 16-bit integer variable named value.

Embedded C

uint16_t [1] = 0x1234;

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Aval

Bvalue

Cnum

Ddata

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name than 'value'.

The variable is named value as required.

2fill in blank

medium

Complete the code to create a pointer to the first byte of value.

Embedded C

uint8_t *ptr = (uint8_t *) &[1];

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Avalue

Bnum

Cdata

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name other than 'value'.

The pointer ptr points to the address of value.

3fill in blank

hard

Fix the error in the code to correctly print the first byte of value in hexadecimal.

Embedded C

printf("First byte: 0x%[1]\n", *ptr);

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AX

Bx

Cd

Do

Attempts:

3 left

💡 Hint

Common Mistakes

Using decimal (%d) or octal (%o) format specifiers.

The format specifier %X prints the number in uppercase hexadecimal.

4fill in blank

hard

Fill the blank to create a function that checks if the system is little-endian.

Embedded C

int is_little_endian() {
    unsigned int num = 1;
    return *((unsigned char *) &num) [1] 1;
}

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A<

B!=

C>

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using inequality or wrong comparison operators.

The function returns true if the first byte equals 1, indicating little-endian.

5fill in blank

hard

Fill all three blanks to create a function that swaps the byte order of a 16-bit integer.

Embedded C

uint16_t swap_bytes(uint16_t val) {
    return (val [1] 8) | ((val [2] 8) & [3] 0xFF00);
}

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A<<

B>>

C&

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong shift directions or missing masking.

The function shifts the upper byte right and the lower byte left, then masks the upper byte.