This
int **tab2 = new int*[3];
does not do what you think it does.
You want an array that will contain TEN (10) pointers, each to an array of THREE ints.
new int*[3]
is an array that contain THREE pointers.
What you want is this (live at coliru):
#include <iostream>
int main() {
int **tab2 = new int*[10];
for(int i = 0; i < 10; i++) {
tab2[i] = new int[3];
tab2[i][0] = 40;
tab2[i][1] = 10;
tab2[i][2] = 100;
}
for(int i = 0; i < 10; i++) {
delete [] tab2[i];
}
delete [] tab2;
}