Question

The purpose of this project is to practice the pthread built in functions.

The following c program is a simple program to make a matrix of integers and print it.

//File name: a.c

#include <stdio.h>

#include <time.h>

#include <stdlib.h>

int** a;

int main(){

time_t t;

int m, n, i, j;       //m is the numbers of rows and n is the number of columns.

printf("Enter the number of rows, and columns: ");

scanf("%d%d", &m, &n);

printf("%d, %d\n", m, n);

srand((unsigned) time(&t));

a=(int**) malloc(m*sizeof(int*));

for(j = 0; j < n; j++)

    a[j] = (int*) malloc(n * sizeof(int*));

for(i = 0; i < m; i++)

    for(j = 0; j < n; j++)

      a[i][j] = rand() % 1000;

for(i = 0; i < m; i++){

    for(j = 0; j < n; j++)

      printf("%d,", a[i][j]);

    printf("\n");

}

return 0;

}

Your project uses pthread built-in functions based on the following conditions:

1. The program reads from the console the number of rows and the number of columns (like the above program). Therefore, the matrix has m rows and n columns.

2. The program creates m threads.

3. Each thread assigns random numbers to one row of the matrix.

4. The function main, sorts each row.

5. Each thread displays its sorted row.

6. The function: main displays the entire matrix.

Answer:

Answer 1

To compile

gcc a.c -pthread

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include<pthread.h>
#include<unistd.h>
int** a;


// a structure for passing argument in thread
typedef struct {
    int row;
    int col;
}args;
int cmpfunc (const void * a, const void * b) {
   return ( *(int*)a - *(int*)b );
}
void* fun(void * arg){
    args* temp = (args *)arg;
    qsort(a[temp->row],temp->col,sizeof(int),cmpfunc);
    for(int i=0;i<temp->col;i++)printf("%d,",a[temp->row][i]);
    printf("\n");
    return NULL;

}


int main(){
    time_t t;
    int m, n, i, j;       //m is the numbers of rows and n is the number of columns.
    printf("Enter the number of rows, and columns: ");
    scanf("%d%d", &m, &n);
    printf("%d, %d\n", m, n);
    srand((unsigned) time(&t));
    a=(int**) malloc(m*sizeof(int*));
    for(j = 0; j < n; j++)
        a[j] = (int*) malloc(n * sizeof(int*));
    for(i = 0; i < m; i++)
        for(j = 0; j < n; j++)
          a[i][j] = rand() % 1000;
    pthread_t tid[m];
    for(int i=0;i<m;i++){
        args arg ;
        arg.row = i;
        arg.col = n;
        pthread_create(&tid[i],NULL,fun,(void *)&arg);
        usleep(1000);  // applied micro sleep so that thread returns correctly
    }
    for(int i=0;i<m;i++){
        pthread_join(tid[i],NULL);
    }
    printf("\n");
    printf("\n");
    printf("By main thread\n");
    printf("\n");
    for(i = 0; i < m; i++){
        for(j = 0; j < n; j++)
          printf("%d,", a[i][j]);
        printf("\n");
    }
    return 0;
}