question about two dimensional arrays

[Basit781]

Hi to all,
Hope you all will be fine.I am confused about Arrays . Consider this, it's a single dimensional integer array

int product_codes[3] = {10, 972, 45};

Also character array

char name[] = {'S', 'a', 'm', '\0'};

See, For initialize single dimensional array we use one set of curly({ }) braces and separate each character with comma(,).

But what about this

 char Ones[10][10] = {"One", "Two","Three","Four","Five","Six","Seven","Eight","Nine"};

See, in this we also use singe set of curly braces and separate each character with comma(,), but it's not a single dimension, it's a two dimensional array. How and why?

If we declare it like this i get an error

 char Ones[10] = {"One", "Two","Three","Four","Five","Six","Seven","Eight","Nine"}; //Error

Can someone please explain to me why we declare it with two dimension and why i getting error while creating it with single dimension.

It's a two dimension array

int matrix[2][4] ={ {1, 2, 3, 4}, {10, 20, 30, 40} };

We used two set of curly braces inside a single set of curly braces to initialize two dimensional array but we didn't initialize {"One", "Two",....} array in this manner why?

Thanks

[TheRogue]

char Ones[10][10] = {"One", "Two", ...

'O' 'n' 'e' '/0' == 4 * char
'T' 'w' 'o' '/0' == 4 * char

Each comma is separating an array of characters.

char name[] = {'S', 'a', 'm', '\0'};

could be written as

char name[]   = "Sam" ;
char name[10] = "Sam" ;

[Basit781]

Hi,
Thanks. You mean the code

 char Ones[10][10] = {"One", "Two","Three","Four","Five","Six","Seven","Eight","Nine"};

is equivalent to

char Ones[10][10] ={{'O', 'n', 'e', '\0'}, {'T', 'w', 'o', '/0'}, {'T', 'h', 'r', 'e', 'e', \0'}, .....};

Means each string("One", "Two",...) is itself a separate character array separated by commas as i did above.

Thanks

[Lindley]

Effectively yes, a string literal is a special form of char array.

The primary difference between the {'a', '\0'} notation and the "a" notation is that while the former may only be used in initialization, the latter may be used anywhere:

char str[] = {'a', '\0'};
strcpy(str, "b");

Also, it is not necessary to copy string literals into a variable; you can simple point at their location in (probably read-only) memory instead. But better make sure you do so in a const manner or you risk ugly problems:

const int *i = {1,2,3}; // NOT possible
int i2[] = {1,2,3}; // just fine, the array is copied to the stack
const char *s = "Hello"; // just fine, so long as s is a const char*
char *s2 = "World"; // the compiler will accept this, but it's a bad idea because attempting to modify the string literal "in-place" without copying it to the stack will likely crash your program
char s3[] = "Test"; // just fine, the literal is copied to the stack