Storing returned values of a function as structure array in C [duplicate]

Question

I have a function that prints out 11 points of a quadratic function ax^2 + bx + c with a, b, c as input. The function works fine except I need to use structures, not just variables x and y. How can I get my function to return a structure value and store it in a structure array then print out the structure array?

struct point {
    int x;
    int y;
};
struct point *findpoint(int a, int b, int c){
  int i, x, y;
  x = -5;
  for  (i = 0; i < 11; i++)
  {
    y = (a * (x * x)+ (b * x) + c);
    printf("The points are {%d, %d}\n", x, y);
    x++;   
  } 
}

struct point arr_point[11];

int main(int argc, char *argv[]){

struct point *ptr;
  printf("Enter coefficients a, b, c:");
  int a, b, c;
  int i;
  for (i = 0; i < argc; i++){
    scanf("%d %d %d", &a, &b, &c);
  }
  printf("%d %d %d\n", a, b, c);

  findpoint(a, b, c);
  return 0;
}

Do you want (a) the main routine to create an array of structures, the findpoint routine to return one structure per call, and the main routine to store that structure in its array, (b) the main routine to create an array of structures and the findpoint routine to directly store values in one element of that structure per call, (c) the main routine to create an array of structures and the findpoint routine to store values in all of those structures in one call, (d) the findpoint routine to create an array of structures and return it, filled in, or (e) something else? — Eric Postpischil
– Eric Postpischil, Commented Nov 7, 2020 at 11:31
I'm trying to do the first option (a) where main stores the the structure and prints it — nsh369
– nsh369, Commented Nov 7, 2020 at 19:35

Jose · Accepted Answer · 2020-11-07 11:33:56Z

0

You can create an alias for your struct with typedef:

typedef struct {
  int x;
  int y;
} Foo_t;

Foo_t returnStruct() {
    Foo_t foo = {1,2};
    return foo;
}

int main() {
  const uint8_t SIZE_ARRAY = 2;
  Foo_t arrayFoo[SIZE_ARRAY];

  arrayFoo[0] = returnStruct();
  arrayFoo[1] = returnStruct();
  for(uint8_t i=0;i<SIZE_ARRAY;i++) {
    printf("Index %d: x=%d y=%d \n", i, arrayFoo[i].x, arrayFoo[i].y);
  }
    
}

edited Nov 7, 2020 at 11:33

answered Nov 7, 2020 at 11:27

Jose

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1 Comment

Jose Over a year ago

@DavidCullen Return a pointer to a local variable and return a struct are different things

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