Do I have to return `NULL` for thread function when I use the detached pthread in linux?

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  I put this compile-run.sh in /usr/local/bin for global usage, and when I type the command compile-run.sh XXX.cpp, it intend to compile and run the specified cpp file. But the problem now is I have to manually removed ".cpp" in the command.

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• c++ segmentation fault and Trace/breakpoint trap when using Dynamic memory allocation

  I am practicing Dynamic memory allocation in C++. I wanna enter some word which length is less than 10, and when I enter "-1", it will print the word I have entered before.

  But when I enter more than three words, it will give me an Trace/breakpoint trap or segmentation fault. I use gdb-peda to check my code, it said "double free detected in tcache 2", I think the problem is the "delete" part in my code, but I dont know how to correct it.

  the gdb-peda reply

  this is my code:

  #include <iostream>
  #include <limits>
  using namespace std;
  
  int counter = 0;    //be used to count how many times we have entered
  char **ins();
  
  int main() {
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      for ( int i = 0; i < counter; i++ ) {
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      system( "pause" );
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  char **ins() {
  
      auto dict = new char *[1]();    //total list
      auto cpdict = new char *[1]();    //copy list
  
      while ( 1 ) {
  
          auto word = new char[10]();    //a list be used to store the entered word  (length<10)
  
          cout << "input word: ";
          cin.get( word, 10, '\n' );    //get the entered word in the list
          if ( word[0] == '-' && word[1] == '1' ) {    //if enter "-1" , delete the copy list and return the total list
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              return dict;
          }
          counter++;    //plus one of the times of entering
  
          delete[] dict;    //delete the old total list
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          for ( int i = 0; i < counter - 1; i++ ) *( dict + i ) = *( cpdict + i );    //copy the stuffs in old copy list to new total list
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          delete[] cpdict;    //delter the old copy list
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          for ( int i = 0; i < counter; i++ ) *( cpdict + i ) = *( dict + i );    //copy the stuffs in new total list to new copy list
  
          cin.clear();
          cin.ignore( numeric_limits<std::streamsize>::max(), '\n' );
      }
  }
  

  My imagine input and output is like:

  input word: aaa
  input word: bbb
  input word: ccc
  input word: ddd
  input word: -1
  

  output:

  aaa
  bbb
  ccc
  ddd
  
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• Problem when Handling repeated error values on php and mysql

  I have a PHP program that connect to a MariaDB databse.

  I upload name as "numbers" and i defined the value as UNIQUE so I don´t want to be repeatated.

  However I would like to handle the error when a vlaue is repeated:

  This is the table I created:

  Table in MariaDB

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      -> );
  

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  $username = "xxx";
  $password = "xxx";
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      }
      //header("location:javascript://history.go(-1)");
  }
  

  the code part after if($callToDb->execute()){ it is commented because it is not working but I would like to just show a message when the vlaue is repeated. The same than when a vlaue is registrated correctly.

  The issue to handle duplicate error is in this part which at the moment I am not using in my code as is not working fine:

  if (!$callToDb->execute()) {
      if ($callToDb->errno == 1062) {
          return '<h3 style="text-align:center;">VALUE REPEATED!</h3>';
      }
      else{
         return '<h3 style="text-align:center;">registration submmited!</h3>';
      }
  }
  

  Any idea why this part of the code it is not working?
• httplib2 :- argument should be integer or bytes-like object, not 'str'

  I am using Google Indexing API, and I am getting this error

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  I am implementing the API on the Django server when I run it on my local machine it runs just fine. but when I put it on pythonanywhere it is giving me the above error. I don't know what's the reason for this error. here is the function

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              context['content'] = content
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• Why does my thread stop after printing one line on its second run?

  I'm using pthreads and I'm trying to run an infinite loop on the main thread. The loop is supposed to print out "Hello world!" 10 times, then create a separate thread that writes "Hello moon!" 10 times, and then start over.

  For some reason the output of my program is (always):

  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello moon!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello world!
  Hello moon!
  

  instead of running forever.

  The code follows:

  #include <stdio.h>
  #include <stdlib.h>
  #include <pthread.h>
  #include <unistd.h>
  
  #define SEC_IN_NSEC(x) (x * 1000000000)
  
  pthread_mutex_t mutex;
  
  void *hello_moon(void *param);
  
  int main(int argc, char **argv)
  {
      pthread_t moon_tid;
  
      pthread_mutex_init(&mutex, NULL);
  
      while(1) {
          
          pthread_mutex_lock(&mutex);
  
          for(int i = 0; i < 10; i++) {
              printf("Hello world!\n");
              sleep(1);
          }
  
          pthread_mutex_unlock(&mutex);
  
          pthread_create(&moon_tid, NULL, hello_moon, NULL);
          pthread_join(moon_tid, NULL);
      }
  
      pthread_mutex_destroy(&mutex);
  }
  
  void* hello_moon(void *param)
  {
      struct timespec ts;
      ts.tv_nsec = SEC_IN_NSEC(0.2); // 0.2 s in ns
      
      pthread_mutex_lock(&mutex);
  
      for(int i = 0; i < 10; i++) {
          printf("Hello moon!\n");
          nanosleep(&ts, NULL);
      }
  
      pthread_mutex_unlock(&mutex);
      pthread_exit(0);
  }
  

  Does anyone have a clue why this is happening?

  UPDATE: I commented out the sleep and nanosleep calls and ran it, then it loops as expected. I still want the delay between prints, however.
• Multithreading Problem - Not understanding how the concept of printf implemented in concurrency

  Im struggling a problem in multithreading which I have two threads running over one printf ; and I don't know how exactly those four cases that's already explained in that video are correct?! could anyone please illustrate more about them? appreciated for any help to understand why what's explained here to that problem is correct ! I'm attaching down the video of the problem: enter link description here

  Appreciated for any help for how those 4 cases of the problem are correct .
• Setting priority with pthread_attr_setschedparam doesn't seem to change NICE value

  I would like to create a thread that has lower priority than its parent.

  I came up with following code with a hope that the thread has 5 for its NICE value.

        pthread_attr_t tattr;
        struct sched_param param;
  
        if(pthread_attr_init(&tattr) != 0)
        {
           print("Thread_Create: Error pthread_attr_init \n");
        }
  
        if(pthread_attr_getschedparam(&tattr, &param) != 0)
        {
           print("Thread_Create: Error pthread_attr_getschedparam \n");
        }
  
        if(pthread_attr_setschedpolicy(&tattr, SCHED_RR) != 0)
        {
           print("Thread_Create: Error pthread_attr_setschedpolicy \n");
        }
  
        param.sched_priority = 5;
  
        if(pthread_attr_setschedparam(&tattr, &param) != 0)
        {
           GeaLog(GeaLogLevel_Emerg, "Thread_Create: Error pthread_attr_setschedparam \n");
        }
  
        pthread_create(&instance->_private.thread, &tattr, Run, instance);
  

  Now, I would like to check if it is effective. I executed ps -m -l [parent pid]

  # ps -m -l 10802
  F S   UID   PID  PPID  C PRI  NI ADDR SZ WCHAN  TTY        TIME CMD
  0 -     0 10802     1 12   -   - - 10362 -      pts/1      0:18 /usr/crank/build
  0 S     0     -     - 12  80   0 -     - hrtime -          0:18 -
  1 S     0     -     -  0  80   0 -     - hrtime -          0:00 -
  

  I was expecting NI to be 5 but it's 0. Do you have any idea what I am missing?