Question with Arrays and Functions

Just a general question. If I have a function(called Function 1). Inside this function I call another function (Function 2, has no parameters). Within Function 2, I create an array and will need to use this array in Function 1. Do I need to return the array(more difficult in C) or can I somehow access the array from Function 1?

You can create the array in Function 1 instead, then pass a pointer to the first element of this array to Function 2.

Originally Posted by laserlight

You can create the array in Function 1 instead, then pass a pointer to the first element of this array to Function 2.

Can't create the array in Function 1. A small sample of what I am doing.

Code:

//header
struct Data{
  
  int size;  
  double meas[50];
 };
 
 struct Data cont;

Code:

int Test (....)
{
//Call Function
StartTest();
....
//use cont.meas[x] array
return 0;
}

Code:

double StartTest(void)
....
....
//Here an array will be created as: cont.meas and want to return this array

I won't be able to test for few more days, just trying to get it correct for now.

Thought about something like this to return array from StartTest

Code:

double *StartTest(void)
{
 double *meas = malloc(50*sizeof(double));

 //create cont.meas array
 return cont.meas;
}

I suspect that you actually want:

Code:

struct Data {
    int size; 
    double *meas;
};

This way, you can write:

Code:

void Data_init(struct Data *data, int size)
{
    data->size = size;
    data->meas = malloc(size * sizeof(data->meas[0]));
}

void Data_destroy(struct Data *data)
{
    data->size = 0;
    free(data->meas);
    data->meas = NULL;
}

struct Data StartTest(void)
{
    struct Data data;
    Data_init(&data, 50);
    // Populate array through data.meas
    // ...
    return data;
}

That might be. I will give it a shot and report back. Thanks

I am using software with predefined functions and the function creates an array and that array I am trying to return.

I was wondering if this logic will return the array to be able to use in RunTest?

header file

Code:

struct Data{
     double mData[50];
     int size;
 };

 struct Data cMeas;

c file

Code:

int RunTest(x,y,z...)
{
    double *mData;
    int size;

            
            //Run Test
            mData = StartTest();
            
            size = sizeof mData / sizeof mData[0];

            for (int index = 1; index < cMeas.size; index++)
            {
               ..........
              ...........
              ............ cMeas.mData[index-1];
            }

     return 0;
}

double *StartTest(void)
{
     .......
     .......
     double *mData = malloc(50*sizeof(double));

     ......
     ......
     functionReturnsArray(x,y,cMeas.mData,z); //functions takes in values and stores in array

     return cMeas.mData;
}