Thread: malloc pointers within a struct

Hi, I am trying to get this and I know I have to be close.

Code:

#include "stdio.h"
#include "math.h"
#include "ctype.h"

struct temperatures
{
    int *inTemperature;
    int *outTemperature;
};

typedef struct temperatures Temperatures;


int main(int argc, char** argv)
{
    char scale;
    int max;
    int min;
    int interval;
    int dataSize;
    int i;

    while(1)
    {
        printf( "Enter a temperature scale   (F/C): ");
        scanf( " %c", &scale);
        scale = toupper(scale);
        
        if (scale == 'C')
        {
            break;
        }
        if (scale == 'F')
        {
            break;
        }
    }    
    printf( "Enter a minimum temperature   (%c): ", scale);
    scanf( " %d", &min);
    printf( "Enter a maximum temperature   (%c): ", scale);
    scanf( " %d", &max);
    printf( "Enter a temperature interval  (%c): ", scale);
    scanf( " %d", &interval);    
    
    dataSize =  ceil( (float) (max - min) / interval )  + 1; 
    
    Temperatures.inTemperature = malloc(dataSize * sizeof(inTemperature));    
    Temperatures.outTemperature = malloc(dataSize * sizeof(outTemperature));

    for (i = 0; i < dataSize; i++)
    {
        Temperatures.inTemperature[i] = min + (i * interval);
        if (scale == 'F')
        {
            Temperatures.outTemperature[i] = (Temperatures.inTemperature[i] - 32) * 5 / 9;            
            
        }
        if (scale == 'C')
        {
            Temperatures.outTemperature[i] = 32 + (Temperatures.inTemperature[i] * 9 / 5);            
        }
    }
    for (i = 0; i < dataSize; i++)
    {
        Temperatures.inTemperature[i] = min + (i * interval);
        if (scale == 'F')
        {
            printf( "  %3d F  =  %3d C\n", Temperatures.inTemperature[i], Temperatures.outTemperature[i]);
            
        }
        if (scale == 'C')
        {
            printf( "  %3d C  =  %3d F\n", Temperatures.inTemperature[i], Temperatures.outTemperature[i]);
        }
    }
    free (Temperatures);
    Temperatures = NULL;
    return 0;
}

it appears the problem is here:

Code:

Temperatures.inTemperature = malloc(dataSize * sizeof(inTemperature));
Temperatures.outTemperature = malloc(dataSize * sizeof(outTemperature));

I have tried Temperatures = malloc..... and no luck.

Any help would be appreciated.

AFAIK; you haven't created an instance of the struct. typedef only renames the type, doesn't create an instance.

Code:

typedef struct temperatures Temperatures;

// ...

int main()
{
     // ...

     Temperatures temp;
     
     // ...

     temp.inTemperature = malloc(sizeof(int) * dataSize);
}

Man! How could I forget to do that?

...just when I think I am on the right road!

Thank you both for the "GPS" directions!!