C strings

char* b = "hello";

int main() {
    for (int i=0; i<6; i++) {
        printf("char[%d] = '%c' (%d)\n", i, b[i], (int)b[i]);
    }
    return 0;
}

---
C arrays

int a[3] = {1, 2, 3};    // an array of 3 int's
char b[3] = {'a', 'b', 'c'};  // an array of 3 char's

int main() {
  printf("%d\n", a[0]);

  a[1] += 1;  // use index access
  *(a+2) = 5; // pointer access
  printf("%d %d\n", a[1], a[2]);

  // pointers to array elements
  printf("a %p a1 %p a2 %p a2 %p\n", a, a+1, a+2, &a[2]);

  // pointer arithmetic uses type
  printf("%p %p\n", b, b+1);

  return 0;
}

---
struct

struct student {
    int id;
    char *name;
};

int main() {
    struct student t;
    t.id = 1024;
    t.name = "alice";

    struct student *p = &t;
    p->id += 1;

    printf("t.id =%d, t.name =%s\n", t.id, t.name);
    printf("p->id=%d, p->name=%s\n", p->id, p->name);
}

---
factor out

typedef struct {
    int id;
    char *name;
} student;

student *new_student() {
    student a = {1, "bob"};
    return &a;
}

int main() {
    student *p = new_student();
    printf("p->id=%d, p->name=%s\n", p->id, p->name);
}

---
exploit warning

void foo() {
    char *a = "this is just some random string";
    //student a = {99999999, "RANDOM STUDENT"};
}

---
malloc

student *new_student() {
    student *a = (student*)malloc(sizeof(student));
    a->id = 1;
    a->name = "bob";
    return a;
}

---
check memory leak

valgrind --leak-check=full ./your_program


---
main function

int main(int argc, char *argv[]) {
    for (int i=0; i<argc; i++) {
        printf("arg[%d] = %s\n", i, argv[i]);
    }
}