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  1. #include <sys/wait.h>
  2. #include <unistd.h>
  3. #include <sys/shm.h>
  4. #include <sys/ipc.h>
  5. #include <sys/stat.h>
  6. #include <sys/types.h>
  7. #include <iostream>
  8. #include <string>
  9. using namespace std;
  10.  
  11.  
  12. int main(){
  13.         string  s="Hello, World!";
  14.  
  15.         pid_t pid;
  16.         int shm_id;
  17.         if((shm_id=shmget(IPC_PRIVATE,sizeof(int),IPC_CREAT|0666))<0){
  18.                  perror("shmget");
  19.                  return 0;
  20.         }
  21.         int *shm_addr;
  22.         if((shm_addr=(int *)shmat(shm_id,NULL,0))==(int*)-1){
  23.                 perror("shmat");
  24.                 return 1;
  25.         }
  26.  
  27.         for(int i=0;i<s.size();i++){
  28.                 pid=fork();
  29.                 if(pid==-1)
  30.                         cout<<"fork error"<<endl;
  31.                 else if(pid==0)
  32.                         break;
  33.                 else
  34.                         continue;
  35.         }
  36.  
  37.         if(pid>0){
  38.                 for(int i=0;i<s.size();++i)
  39.                         wait(NULL);
  40.                 sleep(1);
  41.                 if((shmctl(shm_id,IPC_RMID,0))==-1){
  42.                         perror("shmctl");
  43.                         exit(-1);
  44.                 }
  45.                 cout<<endl;
  46.  
  47.         }else{
  48.  
  49.                 int *sp=(int*)shmat(shm_id,NULL,0);
  50.                 sleep(2);
  51.                 cout<<s[*sp];
  52.                 (*sp)++;
  53.                 exit(0);
  54.         }
  55.         return 0;
  56. }
Success #stdin #stdout 0s 15248KB
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stdin
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Standard input is empty
stdout
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Hello, World!
https://ideone.com/9RI620
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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