Xcode error message not making logical sense [closed] - c

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about programming within the scope defined in the help center.
Closed 1 year ago.
Improve this question
I'm supposed to be generating a program that creates a thread that generates a random number between 0 and 1 and prints out the generated random number.
The error messages I'm receiving from Xcode don't make any logical sense. I tried many different methods, I might just be overlooking it but I could don't see any possible syntax errors
#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
void printMsg(char* msg) {
int status = 0;
printf("%s\n", msg);
pthread_exit(&status);
}
int main(int argc, char** argv) {
pthread_t thrdID;
int* status = (int*)malloc(sizeof(int));
printf("creating a new thread\n");
pthread_create(&thrdID, NULL, (void*)printMsg, argv[1]);
printf("created thread %d\n". thrdID);
pthread_join(thrdID, &status);
printf("Thread %d exited with status %d\n", thrdID, *status);
return 0;
}

Answer 1

Oh, I see it now, you had a period instead of a comma here:
printf("created thread %d\n". thrdID);
should be
printf("created thread %d\n", thrdID);
It was pointed out in some now deleted comments, that there were other issues with the code that should be corrected.
These are some suggestions about how to deal with these issues:
#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
void printMsg(char* msg) {
// The stack of the thread will be destryed on exit
// so you need to allocate the status value (or do some
// rather dubious casting... this is cleaner).
int* status_pointer = malloc(sizeof(int));
printf("%s\n", msg);
// For demonstration purposes set it to something other than 0.
*status_pointer = 123;
pthread_exit(status_pointer);
}
int main(int argc, char** argv) {
pthread_t thrdID;
void* status = NULL;
printf("creating a new thread\n");
// You should not blindly pass argv[1] without checking it's valid.
// You can provide a default value like I did below, or error out.
char *msg = argc > 1 ? argv[1] : "This is a default message.";
pthread_create(&thrdID, NULL, (void*)printMsg, msg);
// thrdId is pointer so use the %p format specifier.
printf("created thread %p\n", thrdID);
pthread_join(thrdID, &status);
// same issue with %p
printf("Thread %p exited with status %d\n", thrdID, *(int*)status);
// don't forget to free what you allocated.
free(status);
return 0;
}