fork(2) download 
  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <unistd.h>
  4. #include <string.h>
  5. #include <sys/types.h>
  6. #include <sys/stat.h>
  7. #include <sys/wait.h>
  8. #include <fcntl.h>
  9.  
  10.  
  11. int vf,pmax,SIZE,size,sudoku[25][25];
  12.  
  13. int isValid(int row,int col,int weight)
  14. {
  15.         int i,j,start_row,start_col;
  16.         for(i=0;i<SIZE;i++)
  17.                 if(sudoku[row][i]==weight)
  18.                         return 0;
  19.  
  20.         for(i=0;i<SIZE;i++)
  21.                 if(sudoku[i][col]==weight)
  22.                         return 0;
  23.  
  24.         start_row=(row/size)*size;
  25.         start_col=(col/size)*size;
  26.         for(i=start_row;i<start_row+size;i++)
  27.                 for(j=start_col;j<start_col+size;j++)
  28.                         if(sudoku[i][j]==weight)
  29.                                 return 0;
  30.         return 1;
  31. }
  32.  
  33. void printSolution()
  34. {
  35.         int i,j;
  36.         printf("\n");
  37.         for(i=0;i<SIZE;i++)
  38.         {
  39.                 for(j=0;j<SIZE;j++)
  40.                         printf("%d ",sudoku[i][j]);
  41.                 printf("\n");
  42.         }
  43.         printf("\n");
  44. }
  45.  
  46. void solveSudoku(int row,int col)
  47. {
  48.    int fd2,fd,i,cn,tmp=0,rev,chn=0,anss=0;
  49.    //printf("hi ");
  50.    fd2=open("tmp2",O_RDWR|O_CREAT);
  51.    flock(fd2,LOCK_EX);
  52.    read(fd2,&anss,sizeof(anss));
  53.    printf("anss=  %d\n",anss);
  54.    flock(fd2,LOCK_UN);
  55.    close(fd2);
  56.    if (anss==1) _exit(1);
  57.         if(row==SIZE && col==0)
  58.               {
  59.                 //printf("aaa\n");
  60.                 anss=1;
  61.                 fd2=open("tmp2",O_RDWR|O_CREAT);
  62.                 //flock(fd2,LOCK_EX);
  63.                 write(fd2,&anss,sizeof(anss));
  64.                 printSolution();
  65.                 flock(fd2,LOCK_UN);
  66.                 close(fd2);
  67.                 _exit(1);
  68.               }
  69.         else
  70.         {
  71.                 if(sudoku[row][col]!=0)    //encounters a pre-filled cell.
  72.                 {
  73.                         if (col==SIZE-1) solveSudoku(row+1,0);
  74.                          else solveSudoku(row,col+1);
  75.                 }
  76.                 else
  77.                         for(i=1;i<=SIZE;i++)
  78.                                 if( isValid(row,col,i) && sudoku[row][col]==0)
  79.                                 {
  80.                                         fd=open("tmp",O_RDWR|O_CREAT);
  81.                                         flock(fd,LOCK_EX);
  82.                                         read(fd,&cn,sizeof(cn));
  83.                                         printf("cn pre=%d\n",cn);
  84.                                         if (cn=pmax)
  85.                                         {
  86.                                            sudoku[row][col]=i;
  87.                                            printf("cn no fork=%d\n",cn);
  88.                                            flock(fd,LOCK_UN);
  89.                                            close(fd);
  90.                                            if(col==SIZE-1) solveSudoku(row+1,0);
  91.                                              else solveSudoku(row,col+1);
  92.                                            sudoku[row][col]=0;
  93.                                            //_exit(0);
  94.                                         }
  95.                                         else if (cn<pmax && cn>=0)
  96.                                         {
  97.                                            cn++;
  98.                                            //flock(fd,LOCK_EX);
  99.                                            write(fd,&cn,4);
  100.                                            printf("cn after=%d\n",cn);
  101.                                            flock(fd,LOCK_UN);
  102.                                            close(fd);
  103.                                            pid_t cpid;
  104.                                            cpid=fork();
  105.                                         if (cpid==-1)
  106.                                         {
  107.                                            sudoku[row][col]=i;
  108.                                            if(col==SIZE-1) solveSudoku(row+1,0);
  109.                                              else solveSudoku(row,col+1);
  110.                                            sudoku[row][col]=0;
  111.                                         }
  112.                                          else
  113.                                         if (cpid==0)
  114.                                         {
  115.                                            sudoku[row][col]=i;
  116.                                            if(col==SIZE-1) solveSudoku(row+1,0);
  117.                                              else solveSudoku(row,col+1);
  118.                                            _exit(0);
  119.                                         }
  120.                                        else
  121.                                         if (cpid>0) chn++;
  122.                                      }//cn<pmax
  123.                                 } //for all possible
  124.                                   {
  125.                                      //printf("chn=%d\n",chn);
  126.                                      while(chn--){
  127.                                              wait(&rev);
  128.                                               //if (rev>0) printf("rev%d\n",rev);
  129.                                               //if (tmp==1) _exit(1);
  130.                                               if (WIFEXITED(rev))
  131.                                                  {
  132.                                                      tmp=WEXITSTATUS(rev);
  133.                                                      if (tmp==1)
  134.                                                      {
  135.                                                          anss=1;
  136.                                                          _exit(1);
  137.                                                          //break;
  138.                                                      }
  139.                                                      else
  140.                                                       if (tmp==0)
  141.                                                       {
  142.                                                           printf("*");
  143.                                                           fd=open("tmp",O_RDWR|O_CREAT);
  144.                                                           flock(fd,LOCK_EX);
  145.                                                           read(fd,&cn,sizeof(cn));
  146.                                                           printf("cnp=%d",cn);
  147.                                                           cn--;
  148.                                                           write(fd,&cn,sizeof(cn));
  149.                                                           printf("cnaf=%d",cn);
  150.                                                           flock(fd,LOCK_UN);
  151.                                                           close(fd);
  152.                                                       }
  153.                                                  }
  154.                                           }//chn--
  155.                                   }//parent process
  156.         }
  157. }
  158.  
  159. int main(int argc,char* argv[])
  160. {
  161.         int i,j,fd,fd2;
  162.         for (i=0;i<=2;i++)
  163.         {
  164.             j=2*i+1;
  165.             if (strcmp(argv[j],"-m")==0)
  166.              {
  167.                 if (strcmp(argv[j+1],"vfork")==0) vf=1;
  168.                  else vf=0;
  169.              }
  170.             if (strcmp(argv[j],"-n")==0)
  171.              {
  172.                 SIZE=atoi(argv[j+1]);
  173.              }
  174.             if (strcmp(argv[j],"-p")==0)
  175.              {
  176.                 pmax=atoi(argv[j+1]);
  177.              }
  178.         }
  179.         printf("vf=%d ",vf);
  180.         printf("pmax=%d ",pmax);
  181.         printf("SIZE=%d\n",SIZE);
  182.         //scanf("%d",&SIZE);
  183.         size=SIZE;  SIZE*=SIZE;
  184.         for (i=0;i<SIZE;i++)
  185.          for (j=0;j<SIZE;j++)
  186.            scanf("%d",&sudoku[i][j]);
  187.           printSolution();  //Display inputted sudoku from the file
  188.  
  189.  
  190.         i=0;
  191.         fd2=open("tmp4",O_RDWR|O_CREAT);
  192.         //flock(fd2,LOCK_EX);
  193.         write(fd2,&i,4);
  194.         printf("tmp4=%d\n",i);
  195.         //flock(fd2,LOCK_UN);
  196.         //close(fd2);
  197. //------------------
  198.         /*
  199.         fd=open("tmp",O_RDWR|O_CREAT);
  200.         flock(fd,LOCK_EX);
  201.         write(fd,&i,sizeof(i));
  202.         read(fd,&i,4);
  203.         read(fd,&j,4);
  204.         printf("tmp=%d %d\n",i,j);
  205.         flock(fd,LOCK_UN);
  206.         close(fd);
  207.         char buf[100];
  208.         fd=open("tmp",O_RDWR|O_CREAT);
  209.         flock(fd,LOCK_EX);
  210.         read(fd,buf,4);
  211.         printf("tmp=%s\n",buf);
  212.         flock(fd,LOCK_UN);
  213.         close(fd);
  214.  
  215.         solveSudoku(0,0);*/
  216.         return 0;
  217. }
  218.  
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
prog.cpp: In function ‘void solveSudoku(int, int)’:
prog.cpp:51: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:54: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:65: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:81: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:84: warning: suggest parentheses around assignment used as truth value
prog.cpp:88: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:101: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:144: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:150: error: no matching function for call to ‘flock::flock(int&, int)’
/usr/include/bits/fcntl.h:145: note: candidates are: flock::flock()
/usr/include/bits/fcntl.h:145: note:                 flock::flock(const flock&)
prog.cpp:52: warning: ignoring return value of ‘ssize_t read(int, void*, size_t)’, declared with attribute warn_unused_result
prog.cpp:63: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result
prog.cpp:82: warning: ignoring return value of ‘ssize_t read(int, void*, size_t)’, declared with attribute warn_unused_result
prog.cpp:99: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result
prog.cpp:145: warning: ignoring return value of ‘ssize_t read(int, void*, size_t)’, declared with attribute warn_unused_result
prog.cpp:148: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result
prog.cpp: In function ‘int main(int, char**)’:
prog.cpp:161: warning: unused variable ‘fd’
prog.cpp:186: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result
prog.cpp:193: warning: ignoring return value of ‘ssize_t write(int, const void*, size_t)’, declared with attribute warn_unused_result
stdout 
Standard output is empty
https://ideone.com/2evISg
language:
C++ (gcc 8.3)
created:
13 years ago
visibility:
public

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