C Programming·The fundamentals of memory

Structs and function design

Structs group related data; functions should state who owns what.

Beginner 14 min read Lesson 8 of 300 Challenge included

What you will be able to do

Use struct for a fixed group of related fields.
Return an explicit error enum for recoverable failures.
Document ownership: who allocates and who frees.

In plain English

Pass large structs by pointer to avoid copies, and mark read-only pointers const. A function returns an error code or a sentinel; it should not print and continue as if nothing happened. Keep allocation and freeing close to the same owner.

course.cC

#include <stdio.h>

typedef struct {
    const char *slug;
    const char *title;
    int minutes;
} Course;

void print_course(const Course *course) {
    printf("%s (%s) · %d min\n",
           course->title, course->slug, course->minutes);
}

int main(void) {
    Course html = { "html", "HTML Foundations", 120 };
    print_course(&html);
    return 0;
}

Your turn

Add a course printer

Medium

Define a Course struct and a function that prints title and minutes.

C · starter

typedef struct {
    const char *title;
    int minutes;
} Course;

Check your understanding before moving on.

Knowledge checkQuestion 1

Why pass a large struct as a const pointer?

Select an answer to continue

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