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copied!<p>For a basic example, allocate the <code>teachers</code> array of a <code>Lesson</code> object like this:</p> <pre><code>Lesson lesson; lesson.numberOfTeachers = 10; lesson.teachers = malloc(lesson.numberOfTeachers * sizeof(*lesson.teachers)); </code></pre> <p>And to deallocate:</p> <pre><code>free(lesson.teachers); </code></pre> <p>But you'll probably need to allocate the <code>Lesson</code> objects dynamically too.</p> <pre><code>Lessons lessons; lessons.numberOfLessons = 5; lessons.arr = malloc(lessons.numberOfLessons * sizeof(*lessons.arr)); </code></pre> <p>And then you'll populate in a loop:</p> <pre><code>for (size_t i=0; i<lessons.numberOfLessons; i++) { Lesson *lesson = malloc(sizeof(*lesson)); lesson->numberOfTeachers = 10; lesson->teachers = malloc(lesson.numberOfTeachers * sizeof(*lesson.teachers)); lessons.arr[i] = lesson; } </code></pre> <p>And to deallocate:</p> <pre><code>for (size_t i=0; i<lessons.numberOfLessons; i++) { free(lessons.arr[i]); } free(lessons.arr); </code></pre> <p>You'll also want to populate the rest of the fields, but I'll concentrate on the allocation and leave that to you.</p> <p>In real code you'll want to check the return values of your calls to <code>malloc</code> for errors, and respond accordingly.</p> <p>Reallocation is a little more tricky. Suppose that you want to change the length of the <code>teachers</code> array in a <code>Lesson</code> object. At this point I think you need to start wrapping things up in functions.</p> <pre><code>void SetTeacherCount(Lesson *lesson, int count) { Teacher* newTeachers = realloc(lesson->teachers, count*sizeof(*lesson->teachers)); if (newTeachers == NULL) { // handle error } lesson->teachers = newTeachers; } </code></pre> <p>This gets more tricky when you are reallocating an array that contains elements that also have dynamic memory allocated. You need to make sure that you <code>free</code> any such nested dynamically allocated memory before you reallocate the parent array.</p>

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