CSE240 Lecture 13

Introduction to Programming Languages
Data Structures
(202009)

Transcript

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   CSE 240
   Introduction to Programming Languages
   Lecture 13: Data Structures in C
   Dr. Javier Gonzalez-Sanchez
   javiergs@asu.edu
   javiergs.engineering.asu.edu | javiergs.com
   PERALTA 230U
   Office Hours: By appointment
   

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2. jgs
   struct
   

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3. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 3
   jgs
   struct type
   § A structure is is a composite data type declaration that defines a physically
   grouped list of variables to be placed under one name in a block of memory.
   § It is created by the keyword struct.
   § Similar to a Java class; but DOES NOT allow methods
   

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4. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 4
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   struct type
   struct type_name {
   type1 element1;
   type2 element2;
   . . .
   typen elementn;
   };
   struct type_name a, b;
   // Example
   #include
   struct person {
   char name[30];
   int id;
   };
   void main( ) {
   struct person x, y;
   scanf("%s", x.name );
   scanf("%d", &x.id);
   printf("%s", x.name);
   printf("\n");
   printf("%d", x.id);
   }
   

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5. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 5
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   Arrays of struct
   #include
   struct contact {
   char name[30];
   int phone;
   char email[30];
   };
   struct contact contact_book[100]; // an array of structures
   void main() {
   int index = 0;
   scanf("%d", &contact_book[index].phone);
   scanf("%s", contact_book[index].name );
   scanf("%s", contact_book[index].email);
   printf("\n %d", contact_book[index].phone);
   printf("\n %s", contact_book[index].name);
   printf("\n %s", contact_book[index].email);
   }
   

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6. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 6
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   Pointers to struct
   name
   phone
   email
   x
   struct contact {
   char name[30];
   int phone;
   char email[30];
   };
   main () {
   struct contact x;
   struct contact *y;
   scanf("%s", x.name); //dot with x
   scanf("%d", &x.phone);
   scanf("%s", x.email);
   printf ("%d \n", x.phone);
   y = &x;
   (*y).phone = 101010; //asterisk and dot with y
   y->phone = 404040; // arrow with y
   printf ("%d \n", y->phone);
   }
   y
   

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   Data Structures
   Linked List (malloc and free)
   

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8. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 8
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   Linked List
   #include
   struct node {
   int val;
   struct node * next;
   };
   struct node * head = NULL;
   head = malloc(sizeof(struct node ));
   head->val = 1;
   head->next = malloc(sizeof(struct node ));
   head->next->val = 2;
   head->next->next = NULL;
   struct node * head = NULL;
   head = malloc(sizeof(struct node));
   if (head == NULL) {
   return 1;
   }
   head->val = 1;
   head->next = NULL;
   void print_list(struct node * head) {
   node * current = head;
   while (current != NULL) {
   printf("%d\n", current->val);
   current = current->next;
   }
   }
   

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9. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 9
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   Part 1
   #include
   #include
   struct node {
   int val;
   struct node * next;
   };
   int main() {
   struct node * head = NULL;
   head = malloc(sizeof(struct node ));
   head->val = 1;
   head->next = malloc(sizeof(struct node ));
   head->next->val = 2;
   head->next->next = NULL;
   push (head, 3);
   push (head, 4);
   push (head, 5);
   print_list(head);
   printf("-----\n");
   pop(&head);
   pop(&head);
   pop(&head);
   print_list(head);
   }
   

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10. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 10
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    Part 2
    void push(struct node * head, int val) {
    struct node * current = head;
    while (current->next != NULL) {
    current = current->next;
    }
    current->next = malloc(sizeof(struct node ));
    current->next->val = val;
    current->next->next = NULL;
    }
    

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11. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 11
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    Part 3
    int pop(struct node ** head) {
    int retval = -1;
    struct node * next_node = NULL;
    if (*head == NULL) {
    return -1;
    }
    next_node = (*head)->next;
    retval = (*head)->val;
    free(*head);
    *head = next_node;
    return retval;
    }
    

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12. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 12
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    Part 4
    void print_list(struct node * head) {
    struct node * current = head;
    while (current != NULL) {
    printf("%d\n", current->val);
    current = current->next;
    }
    }
    

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13. Javier Gonzalez-Sanchez | CSE240 | Fall 2021 | 13
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    Questions
    

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14. jgs
    CSE 240 Introduction to Programming Languages
    Javier Gonzalez-Sanchez, Ph.D.
    javiergs@asu.edu
    Fall 2021
    Copyright. These slides can only be used as study material for the class CSE240 at Arizona State University.
    They cannot be distributed or used for another purpose.
    

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