How to initialize 2D array with the same values in C ++

Question

We can use the fill_n function to initialize a 1D array with a value.

int table[20];
fill_n(table, 20, 100);

But how can we initialize a 2D array with the same values.

int table[20][20];
fill_n(table, sizeof(table), 100); //this gives error

+3

Devesh Agrawal 14 oct. 14 at 13:22

3 answers

You can use a pointer to the first element and a pointer to one of the last:

int table[20][20];
int* begin = &table[0][0];
size_t size = sizeof(table) / sizeof(table[0][0]);
fill(begin, begin + size, 100);

+6

juanchopanza 14 oct. 14 at 13:27

std::vector<std::vector<int>> table(20, std::vector<int>(20, 100));

Everything is done and "filled" in the ad. No more code needed.

-1

Some programmer dude 14 oct. 14 at 13:29

manlio · Accepted Answer · 2014-10-14T13:30:26+0000

Using fill_n you can write:

std::fill_n(&table[0][0], sizeof(table) / sizeof(**table), 100);

How to initialize 2D array with the same values ​​in C ++