I know there is already a solution for problem 1, but if there is different way
ID: 3919356 • Letter: I
Question
I know there is already a solution for problem 1, but if there is different way that it can be coded that would be appreciated if posted.
Problem 1
Given a list of N numbers, a priority list (or queue) comprised of these numbers puts the highest number at the front of the list. If two or more numbers are equal then ties are broken by a fixed scheme. The second highest number comes next, etc. Hence the numbers are being sorted in decreasing (more precisely, non-increasing) order. We can also reverse the sorting order so that a lower value means "higher" priority. In many applications, the numbers acting as priorities are part of a more general data structure, in which case these numbers are referred to as a key. For example, each element of the data structure may represent information about a person such as given by the struct
typedef struct person {
unsigned short age;
char *name; // first name, no spaces
struct height {int feet; int inches;} vertical;
int idenifier; // unique identifier
struct person *next;
} person_t;
where the field/member age acts as a key. A data file "person_data.dat" may contain
31 Alice 5 9 111111
64 Bob 6 11 555555
22 Mira 6 3 7171
which are read in and stored as a linked list whose elements are sorted in non-increasing order of age. That is, a priority list where age acts as the key. The first element of the list is pointed to by person_t *head which in the example would be 64 Bob 6 11 555555. The last element, after the file has been read in and processed, is 22 Mira 6 3 7171. The next field of the last element should be NULL to indicate the end of the list.
Write a program that reads data from an input file, whose name is given as a command-line argument, the values of data of type person_t and stores them into a priority queue pointed to by head. Declare person_t * head as global and call
void read_person_data(FILE *fp);
to read the data and organize them as a priority list. The file is opened in main(). read_person_data(), after reading the next 5-tuple age, name, feet, inches, identifier calls
void insert_plist(unsigned short a, char *b, int c, int d, int e);
which inserts the new element into the priority list pointed to by head. insert_plist() traverses the existing priority list until it finds the position where the element (based on its key) should be inserted. insert_plist() calls malloc() to allocate memory for the new element of type person_t. It calls malloc() to allocate space for the name member. main() calls
void write_person_data(FILE *fp);
to output the content of the priority list pointed to by head into a file pointed to by its argument fp. The name of the output file is provided as the second command-line argument of main() which is opened in main(). When two or more records have the same age, insert the one read later from the file at the end of the those read earlier. Store all functions in their own .c file by the same name (e.g., read_person_data.c). Implement and test your code, and submit your work along with Makefile in v20/.
Problem 2
As a continuation of Problem 1, code the following functions that operate on a priority list pointed to by person_t *head.
void search_age_person_data(unsigned short a);
search_person_data() traverses the priority queue pointed to by head and outputs to stdout all elements which match the key (i.e., age) given by a.
void search_height_person_data(int ft1, int inch1, int ft2, int inch2);
search_height_person_data() traverses the priority queue pointed to by head and outputs to stdout all elements whose height lies strictly between ft1 feet inch1 inches and ft2 feet and inch2 inches.
void delete_person_data(unsigned short a, int b);
delete_person_data() traverses the priority queue and removes any element from the list that matches age a and identifier b. Create a dynamic library libmyplist.so and add the functions from Problem 1 and 2. Check that your code works correctly by linking with libmyplist.so.
Explanation / Answer
#include <stdio.h>
#include <stdlib.h> //required for malloc function
#include <string.h>
//structure definition
typedef struct person {
unsigned short age;
char *name; // first name, no spaces
struct height {int feet; int inches;} vertical;
int idenifier; // unique identifier
struct person *next;
} person_t;
person_t *head=NULL;//declared header as global for linked list
//function inserts element into priority list, pointed by head
void insert_plist(unsigned short a, char *b, int c, int d, int e)
{
//code here
person_t *nn=(person_t*)malloc(sizeof(person_t));//allocate new element node
nn->age=a; //assign each parameter to new node nn
nn->name=(char*)malloc(sizeof(char)*20);//allocate char array
nn->name=b;
nn->vertical.feet=c;
nn->vertical.inches=d;
nn->idenifier=e;
nn->next=NULL;
if(head==NULL) //when first insertion
{
head=nn; //new node as header
head->next=NULL; //next is nothing
}
else //when other than first node
{
person_t *temp=head;//temp refers header
person_t *tprev=temp; //prev follows temp
while(temp->age<a && temp!=NULL) //repeat until existing age is less than parameter a, traverse upto greater element is found
{
tprev=temp;
temp=temp->next; //move to next
}
tprev->next=nn;//link new node nn between prev and temp
nn->next=temp;
}
}
//Function reads file
void read_person_data(FILE *fp)
{
unsigned short a;
char *b=(char*)malloc(sizeof(char)*2);//allocate memory
int c,d,e; //declare local variable for reading
fscanf(fp,"%hu%s%d%d%d",&a,b,&c,&d,&e);//read first element from file
while(!feof(fp)) //repeat unitl end of file
{
insert_plist(a,b,c,d,e);//call function to add element
fscanf(fp,"%hu%s%d%d%d",&a,b,&c,&d,&e);//read second element onwards from file
}
}
//Function writes to another file
void write_person_data(FILE *fp)
{
person_t *temp=head;//temp refers header
while(temp!=NULL) //traverse upto null
{
fprintf(fp,"%hu %s %d %d %d",temp->age,temp->name,temp->vertical.feet,temp->vertical.inches,temp->idenifier);//write data of element from list to file
temp=temp->next;//move to next element
}
}
//Function main with command line args
int main(int argc,char *argv[])
{
if(argc!=3) //when invalid no.of args
{
printf(" Usage: read_person_date <source file> <destination file> ");//print error message
}
else //when proper args are passed
{
FILE *infile=fopen(argv[1],"r");//open file for reading
FILE *outfile=fopen(argv[2],"w");//open file for writing
read_person_data(infile);//call function to read file to linked list
write_person_data(outfile);//call function to write file
fclose(infile);//close the file
fclose(outfile);//close the file
printf(" File is successfully sorted and copied!!!");
}
return 0;
}