Procedural Programming

Transcription

1 Exercise 6 (SS 2016) What will I learn in the 6. exercise Math functions Dynamic data structures (linked Lists) Exercise(s) 1

2 Home exercise 4 (3 points) Write a program which is able to handle students exam results. The data for an exam are: - Mark: Exam identifier : simple number 6 digits - Matriculation-No.: simple number 6 digits Requirements: The program asks for the number of students. The program reserves memory via malloc in dependency of the number of students. The program aks for all students all data (Mark, Exam-ID, Matr). The program determines the number of passed (Mark <= 4.0) results. Home exercise 5 (3 points) Write a program which writes n datasets to an empty file named output.txt. One data set consists of: x (integer), y (integer), z (integer), r (float) The number (n) of data sets and the data set values are entered via console. At first the user is asked how many data sets he wants to enter (input of n). Afterwards he is asked to enter the values for the n data sets. The data sets should be written (line by line) into the file in the form: x;y;z;r Example for an output.txt file (with n=3): 2;5;6;7.87 0;2;50; ;3;79;0.53 2

3 Mathematical functions In math.h a lot of useful mathematical functions are declared Trigonometric functions like sin, cos Hyperbolic functions like sinh, cosh Exponential and logarithmic functions like exp or log Power functions like pow, sqrt Rounding functions like ceil, floor Some hints regarding mathematical operations Take always care that you work with the data types Never use implicit type conversion example: int a=1,b=4; float r; r=a/b; //the result of a/b is an int printf( r=%f,r) //prints 0 Take care if you compare floating point values 3

4 Exercise 10 A program should be created which determines the tangens of an entered degree. Dynamic data structures are useful if the amount of data is unkown can grow and shrink in dependency of our needs requires memory handling - allocation of new memory for new elements - release (free) memory of elements which are not longer used examples: binary trees, linked lists 4

5 Binary tree Hierachical data structure with a set of connected nodes with at most two children Node with no predecessor is root node Nodes with successors are internal nodes. Children of internal nodes are and and they are ordered Nodes without successors are so called leafs Used for searching, sorting Binary tree (Example) root 5 4 Inner node 7 1 leaf NULL NULL NULL NULL NULL NULL NULL NULL 5

6 Decalaration of a Binary tree node Definition of a structure for binary tree. Stored data in an element is only one integer value i; typedef struct nodestruct int i; struct nodestruct *; struct nodestruct *; node; node *root;//root of tree Linked lists Linear search for simple linked list, Quick insert (at the beginning or at the end) Slow insert (for sorted lists, search necessary) Different types: - simple linked list - double linked list - skip lists - adaptive lists Example:Stack (LIFO), queue (FIFO) 6

7 Linked list (declaration of list element) Definition of a structure for a linked list. Stored data in an element is only one integer value data. typedef struct elementstruct int data; struct elementstruct *next; element; element *root=null; //Root of our list Example: list with 2 Elements root Points to the begin of the list 1 list element 4 next 2 list element 8 next NULL marks the end of the list Linked list (append) Append means that a new element should be added to the end of the list. Example: 10 is appended New element must be allocated (malloc) next of 2nd element refers now to the new 3rd element next of new (3rd) element refers to NULL new (3) list lement 1 list element 2 list element 10 next root Points to the begin of the list 4 next 8 next data pointer NULL marks the end of the list 7

8 Linked list (insert) Insert means that a new element should be added to the list at a special position. Example: insert 9 New element must be allocated (malloc) 2nd element next refers now to the new 3rd element New (3rd) element next refers to 4th element new (3) list element 9 next 1 list element 2 list element data pointer 4 list element root Points to the begin of the list 4 next 8 next 10 next NULL marks the end of the list Linked list (delete) Delete means that an element is removed. Remove 8 Element must be localised (typically y by its content) run through list til element is found 1nd element next refers now to the 3rd element Memory for the 2nd element can be released (free) 2 list element 8 next root 4 next 9 next Points to the begin of the list 1 list element data pointer data pointer 3 list element data pointer 4 list element 10 next NULL marks the end of the list 8

9 Exercise 11 A program which manages a sorted linked list. The user is able to input integer values into the list and to delete elements of the list (by its number). The program should use functions to deal with the list: insert(int i); display(); size(); delete(int i); //Inserts a new element with value I //display alle values of the list //shows the number of list elements //deletes the element with value i The user can choose the operation by a number 1 = insert, 2 = display, 3=size, 4=delete, 5=EXIT 9

10 Exercise 10 #include <stdio.h> #include <math.h> #include <stdlib.h> #define PI int main() double sina, cosa,tana, alphad, alphar; double tana2; printf("input alpha(degrees):"); scanf("%lf",&alphad); //Alpha in Radians 1Rad = 180 Degree/PI alphar = alphad * PI / 180.0; tana=tan(alphar); sina=sin(alphar); cosa=cos(alphar); tana2=sina/cosa; printf("\ntan(%.2lf)=%lf",alphad,tana); printf("\nsin(%.2lf)/cos(%.2lf)=%lf",alphad,alphad, tana2); if (tana == tana2) printf("\nresults are equal"); return EXIT_SUCCESS; 2

11 Exercise 11 #include<stdio.h> #include<stdlib.h> // Define a new datatype node which // builds the structure for a node element typedef struct nodestruct int data; struct nodestruct *next; node; //List begin node *head = NULL; // function creates a new node element and assigns the values for // the new element. Returns a pointer to new node. node *newelement(int num, node *next) node *newnode; newnode = (node *)malloc(sizeof(node)); newnode->data =num; newnode->next = next; return newnode; //A function to insert a new node (data = num) in our list void insert(int num) node *currp = head; if (head == NULL) //first element head = newelement(num, NULL); if (num < head->data) //insert as new first element head = newelement(num,head); currp = head; while(currp->next!= NULL) if(currp->next->data < num) currp = currp->next; break; //if currp->next=null then the new element is the new last // element of our list otherwise we insert in the middle of the //list according to the position for the new Element currp->next= newelement(num, currp->next); 4

12 //function deletes a node from our list int delete(int num) node *currp = head, *prev; while(currp!=null) if(currp->data == num) if(currp == head) head = currp->next; prev->next = currp->next; free(currp); return 1; prev = currp; currp = currp->next; return 0; //function displays the values of all list nodes void display(node *n) for( ; n!= NULL; n=n->next) printf("%d ", n->data); //function counts the number of nodes int nodecount(node *n) int count = 0; for(count=0;n!= NULL; n=n->next) count++; return count; /* the main function */ int main() int choice,num; head = NULL; while(1) printf("\nlinked list Operations\n"); printf(" \n"); printf("1.insert\n"); printf("2.display\n"); printf("3.size\n"); printf("4.delete\n"); printf("5.exit\n"); 5

13 printf("please enter your choice: "); if(scanf("%d",&choice)<=0) printf("enter only an Integer\n"); exit(0); switch(choice) case 1: printf("enter the data values to be placed in a node: "); scanf("%d", &num); insert(num); break; case 2: if(head == NULL) printf("the list is Empty\n"); printf("the data values in the list are: "); display(head); printf("\n"); break; case 3: printf("the size of the list is: %d\n", nodecount(head)); break; case 4: if(head == NULL) printf("the list is Empty\n"); printf("enter the value to be deleted: "); scanf("%d", &num); if(delete(num)) printf("%d deleted successfully\n", num); printf("%d not found in the list\n", num); break; case 5: return 0; default: printf("invalid option!\n"); return 0; 6