Can anyone teach me how to assign a empty array to zero? Which means that some of the
c[x][y] have not assigned to a value.

int x = 4;
int y = 4;
a[x] = {30,40,50,60};
b[y] = {100,20,60,40};
c[x][y];
int i = 0;
int j = 0;
while(i<x && j<y){
if(a[i]<b[j]){
c[i][j] = a[i];
}
}

int x = 4;
int y = 4;
a[x] = {30,40,50,60};
b[y] = {100,20,60,40};
c[x][y];
int i = 0;
int j = 0;
while(i<x && j<y){
if(a[i]<b[j]){
c[i][j] = a[i];
else if(a[i]>b[j]){
c[i][j] = b[j];
}
}
}

what i mean is not all the arrays of c[][] are assigned to a value, and after that i need to display it out on a table, but the computer juz simply give me a random value of the unassigned array.like.

Is it safe to assume that there is more to this code somewhere? I ask this because the index values never get changed in the code as given, which would result in an endless loop.

As for initializing the arrays to zero, the best approach is the one given by Gerard4143 earlier: iterate through the array of arrays and clear all of the values, before using them arrays. If you want a general solution to clearing blocks of memory (which is exactly what arrays are), you can use memset().

So I am having trouble knowing what to return in the bottom method any help would be appreciated .
Here are the specifications for completing the StringArray class: