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  1. #include<stdio.h>
  2. #include<pthread.h>
  3. #include<stdlib.h>
  4. #include<unistd.h>
  5.  
  6. pthread_mutex_t mutex, wrt;
  7. int s, rcount = 0;
  8.  
  9. void *writer(void *arg){
  10.         pthread_mutex_lock(&wrt);
  11.         int n = rand() % 10;
  12.         int d = ((int)arg);
  13.         printf("--------------------------------------------------\n");
  14.         printf("W%d Wait for Random time between 0ns and 10ns = %d\n", d, n);
  15.         sleep(n);
  16.         printf("Enter the number of time W%d want to write:\n", d);
  17.         int t;
  18.         scanf("%d", &t);
  19.         printf("Now W%d is writing... i.e. ADDING...\n", d);
  20.         int j;
  21.         for(j=0; j<t; j++){
  22.                 printf("Enter the %dth INTEGER value to write:\n", (j+1));
  23.                 int u;
  24.                 scanf("%d", &u);
  25.                 s = s + u;
  26.         }
  27.         printf("UPDATED value of Shared variable = %d \n", s);
  28.         printf("--------------------------------------------------\n");
  29.         pthread_mutex_unlock(&wrt);
  30. }
  31.  
  32. void *reader(void *arg){
  33.         //Entry Part
  34.         pthread_mutex_lock(&mutex);
  35.         rcount++;
  36.         if(rcount==1){
  37.                 pthread_mutex_lock(&wrt);//No writer should come
  38.         }
  39.         pthread_mutex_unlock(&mutex);//so next reader can come
  40.         //Exit Part
  41.         int n = rand() % 10;
  42.         int d = ((int)arg);
  43.         printf("R%d wait for Random time between 0ns and 10ns = %d\n", d, n);
  44.         sleep(n);
  45.         printf("Enter the number of time R%d want to read:\n", d);
  46.         int t;
  47.         scanf("%d", &t);
  48.         printf("Now R%d is reading....\n", d);
  49.         int j;
  50.         for(j=0; j<t; j++){
  51.                 printf("R%d read the shared value = %d\n", d, s);
  52.         }
  53.         printf("Number of Readers present = %d\n", rcount);
  54.         pthread_mutex_lock(&mutex);
  55.         rcount--;
  56.         if(rcount==0){//Now writer can come if they want
  57.                 pthread_mutex_unlock(&wrt);
  58.         }
  59.         pthread_mutex_unlock(&mutex);
  60. }
  61.  
  62. void main(){
  63.         printf("Enter the 'INTEGER' Initial value of share variable: \n");
  64.         scanf("%d", &s);
  65.         printf("---------------------------------------------\n");
  66.         int rn, wn, i;
  67.         printf("Enter the no. of Reader:\n");
  68.         scanf("%d", &rn);
  69.         for(i=0; i<rn; i++){
  70.                 printf("R%d\n", i);
  71.         }
  72.         printf("---------------------------------------------\n");
  73.         printf("Enter the no. of Writer:\n");
  74.         scanf("%d", &wn);
  75.         for(i=0; i<wn; i++){
  76.                 printf("W%d\n", i);
  77.         }
  78.         printf("---------------------------------------------\n");
  79.  
  80.         pthread_t r[rn], w[wn];
  81.         pthread_mutex_init(&wrt, NULL);
  82.         pthread_mutex_init(&mutex, NULL);
  83.  
  84.         if(rn<0 || wn<0){
  85.                 printf("Sorry: You have Entered NEGATIVE number of READER | WRITER\n");
  86.                 printf("Program is Terminating....\n");
  87.                 return;
  88.         }else if(rn == 0){
  89.                 printf("Sorry: You have not taken any READER\n");
  90.                 printf("No READER thread will be creaded\n");
  91.         }else if(wn == 0){
  92.                 printf("Sorry: You have not taken any WRITER\n");
  93.                 printf("No WRITER thread will be creaded\n");
  94.         }else{
  95.                 printf("Thread Creating....\n");
  96.         }
  97.         printf("---------------------------------------------\n");
  98.  
  99.         if(wn==rn){
  100.                 for(i=0; i<wn; i++){
  101.                         pthread_create(&w[i], NULL, &writer, (int *)i);
  102.                         pthread_create(&r[i], NULL, &reader, (int *)i);
  103.                 }
  104.                 for(i=0; i<wn; i++){
  105.                         pthread_join(w[i], NULL);
  106.                         pthread_join(r[i], NULL);
  107.                 }
  108.         }else if(wn>rn){
  109.                 for(i=0; i<rn; i++){
  110.                         pthread_create(&w[i], NULL, &writer, (int *)i);
  111.                         pthread_create(&r[i], NULL, &reader, (int *)i);
  112.                 }
  113.                 for(i=rn; i<wn; i++){
  114.                         pthread_create(&w[i], NULL, &writer, (int *)i);
  115.                 }
  116.                 for(i=0; i<rn; i++){
  117.                         pthread_join(w[i], NULL);
  118.                         pthread_join(r[i], NULL);
  119.                 }
  120.                 for(i=rn; i<wn; i++){
  121.                         pthread_join(w[i], NULL);
  122.                 }
  123.         }else{
  124.                 for(i=0; i<wn; i++){
  125.                         pthread_create(&w[i], NULL, &writer, (int *)i);
  126.                         pthread_create(&r[i], NULL, &reader, (int *)i);
  127.                 }
  128.                 for(i=wn; i<rn; i++){
  129.                         pthread_create(&r[i], NULL, &reader, (int *)i);
  130.                 }
  131.                 for(i=0; i<wn; i++){
  132.                         pthread_join(w[i], NULL);
  133.                         pthread_join(r[i], NULL);
  134.                 }
  135.                 for(i=wn; i<rn; i++){
  136.                         pthread_join(r[i], NULL);
  137.                 }
  138.         }
  139.         printf("-------------After joining the thread---------\n");
  140.         printf("Final value of share variable = %d\n", s);
  141. }
Success #stdin #stdout 0s 5304KB
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stdin
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Standard input is empty
stdout
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Enter the 'INTEGER' Initial value of share variable: 
---------------------------------------------
Enter the no. of Reader:
---------------------------------------------
Enter the no. of Writer:
---------------------------------------------
Sorry: You have not taken any READER
No READER thread will be creaded
---------------------------------------------
-------------After joining the thread---------
Final value of share variable = 0
https://ideone.com/1qGIgb
language:
C (gcc 8.3)
created:
30 days ago
visibility:
public

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