CODEWITHSUNDEEP
c
CKocar
CKocar

Reputation: 586

String in the Struct

I have a problem and I couldn't find any solution about this. In the example.h I define the struct by this:

#define TOTAL_NUMBER 3

struct{
  float FirstValue[TOTAL_NUMBER];
  float LastValue[TOTAL_NUMBER];

} VALUES;

And I want to use in the example.c like this. 

VALUES.FirstValue={1,2,3}

But I have an error. How can I use like this in the example.c ?

VALUES.FirstValue={1,2,3}

Upvotes: 1

Views: 70

Answers (3)

Lundin
Lundin

Reputation: 213832

You can overwrite previous struct values and set individual members by using compound literals:

typedef struct{
  float FirstValue[3];
  float LastValue[3];

} VALUES;

int main()
{
  VALUES v;
  v = (VALUES) { .FirstValue = {1,2,3} };
}

This is similar to memset all zeroes, followed by memcpy.

Upvotes: -1

4386427
4386427

Reputation: 44274

Well, you can't.

The general syntax

 SomeArrayVariable = {1,2,3};

is valid only as initialization - not as assignment.

Example:

int arr[3];
arr = {1, 2, 3}; // Error - invalid assignment

int arr[3] = {1, 2, 3}; // Fine - valid initialization

Instead you can do:

VALUES.FirstValue[0] = 1;
VALUES.FirstValue[1] = 2;
VALUES.FirstValue[2] = 3;

or you can do like:

struct{
  float FirstValue[TOTAL_NUMBER];
  float LastValue[TOTAL_NUMBER];

} VALUES = {{1, 2, 3}, {0, 0, 0}};

to make it an initialization.

That said.. it's more common to make a typedef'ed struct and then make instances of that type where you need it. This will also allow you to use initialization. Like:

#include <stdio.h>

#define TOTAL_NUMBER 3

typedef struct{
  float FirstValue[TOTAL_NUMBER];
  float LastValue[TOTAL_NUMBER];    
} values_t;

int main(void) {
    values_t values = {{1,2,3}, {0, 0, 0}};
    printf("%f\n", values.FirstValue[1]);
    printf("%f\n", values.LastValue[1]);
    return 0;
}

Upvotes: 5

kiran Biradar
kiran Biradar

Reputation: 12732

You can't assign array as you do for normal variable.

But you can use memcpy to copy the compound literals as below.

memcpy(VALUES.FirstValue, (float[]){1,2,3}, sizeof VALUES.FirstValue);

Upvotes: 1

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