lab17feb22x4B.cpp, C++ (gcc)

lab17feb22x4B.cpp

Language: Layout:

//g++  7.4.0

#include <iostream>

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h> /* perror */
#include <sys/stat.h> /*open */
#include <fcntl.h> /*open*/
#include <string.h> /*strlen*/

using namespace std;

int main()
{   int pid;
 int fd, pid_processo;
 int nread,nwrite,status;
 char st1[256]; /*Stringa lunga 256 caratteri*/
 char st2[256]; /*Stringa lunga 256 caratteri*/
 char fname[]="prova17feb22.txt";
 fprintf(stdout,"Uso: %s nomefile\n",fname);
/* Apertura del file in lettura e scrittura */
 if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
 { perror("opening argv[1]");
   exit(1);
 }
    int valore = 0;
    printf("Unico processo con (PID: %d).\n",getpid());
    pid = fork(); /*Esecuzione fork*/
    if (pid == 0)
    {/* codice eseguito dal figlio */
        printf("Sono il figlio con (PID : %d).\nil processo ( PID: %d) mi ha generato\n",getpid(),getppid());
         printf( "figlio [pid: %d]>>>> valore iniziale= %d\n", getpid(), valore );
         valore += 15;
         printf( "figlio [pid: %d]>>>>> valore finale= %d\n", getpid(), valore); 
    }
else 
    if (pid > 0)
    {/* codice eseguito dal padre */
        printf("Sono il padre con (PID: %d). con un proc. figlio (PID: %d)\n",getpid(),pid);
        printf( "padre [pid: %d]>>>>> valore iniziale= %d\n", getpid(), valore );
        valore += 10;
        printf( "padre [pid: %d]> valore finale= %d\n", getpid(), valore);
    }
    else
    {/* codice eseguito dal padre in caso di errore */
        printf("padre [pid: %d]> problemi durante creazione del figlio.\n",getpid());
        printf("Si e' verificato un errore nella chiamata a fork.\n");
        exit(1);
    }
exit(0);
}

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Compilation time: 0.32 sec, absolute service time: 0,51 sec

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Error(s):

6140358/source.cpp: In function ‘int main()’:
6140358/source.cpp:21:15: error: ‘fnamw’ was not declared in this scope
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
               ^~~~~
6140358/source.cpp:21:15: note: suggested alternative: ‘fname’
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
               ^~~~~
               fname
6140358/source.cpp:21:22: error: ‘O_RDWR’ was not declared in this scope
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
                      ^~~~~~
6140358/source.cpp:21:31: error: ‘O_CREAT’ was not declared in this scope
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
                               ^~~~~~~
6140358/source.cpp:21:40: error: ‘S_IRUSR’ was not declared in this scope
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
                                        ^~~~~~~
6140358/source.cpp:21:50: error: ‘S_IWUSR’ was not declared in this scope
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
                                                  ^~~~~~~
6140358/source.cpp:21:10: error: ‘open’ was not declared in this scope
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
          ^~~~
6140358/source.cpp:21:10: note: suggested alternative: ‘popen’
  if ((fd=open(fnamw, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR))<0)
          ^~~~
          popen
6140358/source.cpp:14:10: warning: unused variable ‘pid_processo’ [-Wunused-variable]
  int fd, pid_processo;
          ^~~~~~~~~~~~
6140358/source.cpp:15:6: warning: unused variable ‘nread’ [-Wunused-variable]
  int nread,nwrite,status;
      ^~~~~
6140358/source.cpp:15:12: warning: unused variable ‘nwrite’ [-Wunused-variable]
  int nread,nwrite,status;
            ^~~~~~
6140358/source.cpp:15:19: warning: unused variable ‘status’ [-Wunused-variable]
  int nread,nwrite,status;
                   ^~~~~~
6140358/source.cpp:16:7: warning: unused variable ‘st1’ [-Wunused-variable]
  char st1[256]; /*Stringa lunga 256 caratteri*/
       ^~~
6140358/source.cpp:17:7: warning: unused variable ‘st2’ [-Wunused-variable]
  char st2[256]; /*Stringa lunga 256 caratteri*/
       ^~~

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