Thread: Struct and malloc array

I want my code to be able to ask for user how many planets the user wants to add to the array of planets, it asks the user how many in the beginning and store it as "numberofinputs" then use that to be the array size using malloc.

But it is giving me the error: request for member name( and dist, and decription) in something not in structure or union.

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct{
  char name[128];
  double dist;
  char description[1024];
} planet_t;
int numberofinputs;


int main() {
//creating the array
printf("How many courses: ");
scanf("%d", &numberofinputs);
int *solarsys=malloc(numberofinputs*sizeof(int));


  int i;
  char name[128];
  printf("Enter planet name to add: ");
  scanf("%s",name);
  
  int have_planet = 0;
  if(!have_planet){

    for (i=0;i<numberofinputs; i++){
    strcpy(solarsys[i].name, name);
    printf("Enter distance and description: ");
    scanf(" %lf ", &solarsys[i].dist);
    gets(solarsys[i].description);
    }
  }


  for(i=0; i<9; i++){
    printf("%s %f %s\n",
           solarsys[i].name,
           solarsys[i].dist,
           solarsys[i].description);
  }


}

solarsys is a pointer to int. It needs to be pointer to planet_t. The argument of malloc() also needs to be numberofinputs*sizeof(planet_t).

C compilers are required to complain if you treat an int as if it was something else.

Warnings about gets() probably reflect the fact that gets() is unsafe (there is no way to prevent it from tromping memory if the user enters too many characters). Using gets() is considered bad practice, to the extent that it is deprecated in the latest C standard (i.e. scheduled for removal completely from C).

Look up the fgets() function for a safer alternative.

Originally Posted by christop

Edit: drat, beat by a few seconds again.

I wasn't aware there was a competition. But, if there is ... <evil chuckle>

You are iterating from 0 to numberofinputs, 'i' is the current index. But you always use numberofinputs as index instead of i with gets. Also use fgets.

Code:

fgets(solarsys[i].description, 1024, stdin);

But preferably, define the max length as a constant instead of a magic number and use it everywhere.

Code:

#define DESCRIPTIONLENGTH 1024;
fgets(solarsys[i].description, DESCRIPTIONLENGTH, stdin);

edit: o i see what u mean with the [i].. thanks!