setting an integer pointer to an integer array and passing arguments to pthread_create

Question

First, I'm not sure how to set an integer pointer to an array. Second, is this the proper way to set pthread_create arguments?

Here's my argument struct:

typedef struct args {
    int *arr;
    int number;
} args;

I created a pointer to the struct:

args *arguments = (args *)malloc(sizeof(args));

I need to set each element of args.arr to argv (command line argument) as an integer. I don't quite understand how to set each element of args.arr:

for(i = 1; i < argc; i++)
    arguments->arr[i] = atoi(argv[i]); // Edit: Segmentation fault on this line

I created an array of threads:

pthread_t threads[4];

..and pass the arguments to each function call:

for(i = 0; i < 4; i++)
    pthread_create(&threads[i], NULL, func, arguments);

Please don't say "this doesn't work" without saying what doesn't work. It's utterly unhelpful. — Kerrek SB
– Kerrek SB, Commented Oct 20, 2013 at 22:21

SheetJS · Accepted Answer · 2013-10-20 22:22:29Z

1

arr is an int pointer, so you need to allocate it first:

arguments->arr = malloc(argc * sizeof(int));

Then you can assign properly:

for(i = 1; i < argc; i++)
    arguments->arr[i] = atoi(argv[i]);

answered Oct 20, 2013 at 22:22

SheetJS

23k12 gold badges68 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Gavin Smith · Accepted Answer · 2013-10-20 22:22:20Z

1

It does not look like you have initialized the value of arguments->arr to point at a valid int.

answered Oct 20, 2013 at 22:22

Gavin Smith

3,1741 gold badge23 silver badges27 bronze badges