Question

Why next code gives me stack around variable x was corrupted?

char x[1][21];
char *ch = x[1];
strcpy(ch,"12345678901234567890");

for (int i = 0; i < 20; i++)
    cout << i << ": " << &x[1][i] << " " << x[1][i] << endl;

output:

0: 12345678901234567890 1
1: 2345678901234567890 2
...

Answer 1

char *ch = x[1]; //error - index out of range

It is wrong. You should write:

char *ch = x[0]; //ok  - index within range

as x is declared as char x[1][21] which means 0 is the only valid index for first dimension. 1 falls out of range.