sizeof and memory budgeting in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print the size of an int variable in bytes.

Embedded C

#include <stdio.h>

int main() {
    int x;
    printf("Size of int: %zu bytes\n", sizeof([1]));
    return 0;
}

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Ax

Bsizeof

Cint

D&x

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name without declaration

Using the address operator & inside sizeof incorrectly

The sizeof operator expects a type or variable. Using int gives the size of the int type.

2fill in blank

medium

Complete the code to calculate total memory needed for an array of 10 floats.

Embedded C

#include <stdio.h>

int main() {
    size_t total_size = 10 * sizeof([1]);
    printf("Total memory: %zu bytes\n", total_size);
    return 0;
}

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Aint

Bdouble

Cchar

Dfloat

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong type inside sizeof

Forgetting to multiply by the number of elements

We want the size of a float because the array holds floats.

3fill in blank

hard

Fix the error in the code to correctly print the size of a pointer to char.

Embedded C

#include <stdio.h>

int main() {
    char *ptr;
    printf("Size of pointer: %zu bytes\n", sizeof([1]));
    return 0;
}

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A*ptr

Bptr

Cchar

D&ptr

Attempts:

3 left

💡 Hint

Common Mistakes

Using *ptr inside sizeof instead of ptr

Using &ptr which is pointer to pointer

To get the size of the pointer itself, use the pointer variable ptr. Using *ptr gives size of the char it points to.

4fill in blank

hard

Fill both blanks to create a dictionary (struct) that stores word lengths only if length is greater than 3.

Embedded C

#include <stdio.h>
#include <string.h>

struct WordLength {
    char word[20];
    int length;
};

int main() {
    struct WordLength wl[5];
    char *words[] = {"cat", "house", "dog", "elephant", "bird"};
    int count = 0;

    for (int i = 0; i < 5; i++) {
        int len = [1](words[i]);
        if (len [2] 3) {
            // store word and length
            count++;
        }
    }
    printf("Words longer than 3: %d\n", count);
    return 0;
}

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Astrlen

Bsizeof

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using sizeof instead of strlen for string length

Using less than operator instead of greater than

Use strlen to get the length of the word, and check if it is greater than 3.

5fill in blank

hard

Fill all three blanks to create a memory budget dictionary for variables with conditions.

Embedded C

#include <stdio.h>

struct MemoryBudget {
    char name[10];
    size_t size;
};

int main() {
    struct MemoryBudget mb[3];
    char *vars[] = {"a", "b", "c"};
    size_t sizes[] = {sizeof([1]), sizeof([2]), sizeof([3])};

    for (int i = 0; i < 3; i++) {
        // store variable name and size
    }
    return 0;
}

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Aint

Bchar

Cfloat

Ddouble

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up types and their sizes

Using variable names instead of types inside sizeof

The sizes array stores sizes of double, char, and float types respectively.