How to give values to arrays in c

Question

I am getting error in the following program. I am unable to figure out why I am not able to store values in the array

main()
{
    int A[10];
    A = {3,1,2,3,4,1,5,8,9,0};
    printArr(A,10);
    printf("\n");

    BubbleSort(A,10);

    printArr(A,10);
    printf("\n----------------Bubble Sort Efficiently ---------------------\n");
    printf("\n");

    A = {3,1,2,3,4,1,5,8,9,0};

    BubbleSortEfficient(A,10);
    printArr(A,10);

    return 0;
}

This is the error I got:

73: error: expected expression before ‘{’ token
80: error: expected expression before ‘{’ token

Please clarify with reason why I am not able to store array elements.

`A={3,1,2,3,4,1,5,8,9,0};` You cannot assign array like this. — johnchen902, Jul 17 '13 at 01:01
73: error: expected expression before ‘{’ token BubbleSort.c:80: error: expected expression before ‘{’ token — Nilesh Agrawal, Jul 17 '13 at 01:02
Related question: http://stackoverflow.com/questions/3137671/declaring-and-initializing-arrays-in-c — Kel, Jul 17 '13 at 01:03

Sergey Kalinichenko · Accepted Answer · 2013-07-17T02:14:15.967

9

ANSI C does not have a syntax for defining array aggregates outside of array initializers. If you combine initialization with the assignment (which technically is not an assignment, but part of initialization) your code will compile:

int A[10] = {3,1,2,3,4,1,5,8,9,0};

Since you cannot reassign arrays, the portion of your program before the second call of BubbleSortEfficient should look like this:

int B[10] = {3,1,2,3,4,1,5,8,9,0};
BubbleSortEfficient(B, 10);
printArr(B, 10);

EDIT : (in response to comment by Keith Thompson) C99 introduces array aggregate expressions, but they cannot be assigned to arrays, because the standard does not have array assignments.

edited Jul 17 '13 at 02:14

answered Jul 17 '13 at 01:02

Sergey Kalinichenko

714,442
84
1,110
1,523

Thanks a lot. Great Fact to note. – Nilesh Agrawal Jul 17 '13 at 01:03
2

C does have array aggregates ("compound literals") starting with C99: `int[]{1, 2, 3, 4, 5}` is a valid expression. But this doesn't do the OP much good, since C doesn't have array assignment. – Keith Thompson Jul 17 '13 at 01:55
1

@KeithThompson Indeed, thanks for a great note! I edited the answer to include your point. Thanks! – Sergey Kalinichenko Jul 17 '13 at 02:15

score 4 · Answer 2 · edited Jul 17 '13 at 01:04

4

Curly braces are used for initialization, not assignment. You should be able to do this:

int A[10]={3,1,2,3,4,1,5,8,9,0};

edited Jul 17 '13 at 01:04

johnchen902

9,531
1
27
69

answered Jul 17 '13 at 01:03

Omegaman

2,189
2
18
30

Is there any other way to aggregate arrays again. – Nilesh Agrawal Jul 17 '13 at 01:05

jxh · Answer 3 · 2013-07-17T04:54:46.470

4

You cannot assign directly to an array, because an array is not a modifiable lvalue. However, if you enclose an array with a structure, then you can assign to a structure.

struct array {
    int a[10];
};

const struct array x = { {3,1,2,3,4,1,5,8,9,0} };
struct array A;
A = x;
BubbleSort(A.a,10);
A = x;
BubbleSortEfficient(A.a,10);

Or, you can use the more traditional memcpy():

int A[10];
memcpy(A, (int[]){3,1,2,3,4,1,5,8,9,0}, sizeof(A));

edited Jul 17 '13 at 04:54

answered Jul 17 '13 at 01:11

jxh

69,070
8
110
193

`int[]{3,1,2,3,4,1,5,8,9,0}` equals `(int[]){3,1,2,3,4,1,5,8,9,0}`? `int[]` means convert the `{3,1,2..}`(array literal) to type `int[]`? – Sayakiss Jul 17 '13 at 03:52
@Sayakiss: Thanks, I corrected the answer, it should be `(int[]){...}`. Yes, that's a compound literal expression. – jxh Jul 17 '13 at 04:55
I Liked the memcpy stuff !! Vote up for it – Nilesh Agrawal Jul 19 '13 at 04:45

score 0 · Answer 4 · answered Jul 17 '13 at 05:29

0

yes you can not assign values to the array like this. You have to assign it as follows,

'int A[10]={3,1,2,3,4,1,5,8,9,0};'

answered Jul 17 '13 at 05:29

Parthiv Shah

350
3
17

How to give values to arrays in c

4 Answers4