CODEWITHSUNDEEP
cpthreadsposix
Ashish Agarwal
Ashish Agarwal

Reputation: 14925

How to pass multiple parameters to a thread in C

I am trying to pass two parameters to a thread in C. I have created an array (of size 2) and am trying to pass that array into the thread. Is this the right approach of passing multiple parameters into a thread ?

// parameters of input. These are two random numbers 
int track_no = rand()%15; // getting the track number for the thread
int number = rand()%20 + 1; // this represents the work that needs to be done
int *parameters[2];
parameters[0]=track_no;
parameters[1]=number;

// the thread is created here 
pthread_t server_thread;
int server_thread_status;
//somehow pass two parameters into the thread
server_thread_status = pthread_create(&server_thread, NULL, disk_access, parameters);

Upvotes: 13

Views: 49290

Answers (2)

paxdiablo
paxdiablo

Reputation: 881113

Since you pass in a void pointer, it can point to anything, including a structure, as per the following example:

typedef struct s_xyzzy {
    int num;
    char name[20];
    float secret;
} xyzzy;

xyzzy plugh;
plugh.num = 42;
strcpy (plugh.name, "paxdiablo");
plugh.secret = 3.141592653589;

status = pthread_create (&server_thread, NULL, disk_access, &plugh);
// pthread_join down here somewhere to ensure plugh
//   stay in scope while server_thread is using it.

Upvotes: 18

Mat
Mat

Reputation: 206679

That's one way. The other usual one is to pass a pointer to a struct. This way you can have different "parameter" types, and the parameters are named rather than indexed which can make the code a bit easier to read/follow sometimes.

Upvotes: 1

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