Trying to fill an array with user input

It doesn't work because you've increment end the index (j) after receiving input and before reading input. You could instead compare nodes[j-1] == -1

Also important, you might overrun your array if you don't put in a maximum number of elements.

Isn't j already incremented when the comparison nodes[j] != -1 is made?

Also, I presume, that we do not want to store the sentinel value -1 into the array.

for( int j = 0; j != NodeMax; ++j) {
    int tmp = 0;
    cin >> tmp;
    if( tmp == -1 ) {
        break;
    }
    node[ j ] = tmp;
}

As @Arun mentioned, j is already increased when nodes[j] != -1 is checked.

Modify as follows:

do {
    cin >> nodes[j];
} while (nodes[j++] != -1);

The statement while (nodes[j] != -1); will never be true because you are incrementing j and moving on the the next index before checking the value. A better approach would be this:

do{
    cin >> nodes[j];
}
while (j < SIZE && nodes[j++] != -1);

nodes[j] isn't the nodes[j] you enter since it has been ++, try this: while(cin>>node[j++]);

You are incrementing j before node[j]!=-1 check. Either do this

int j=-1;
    do{
        j++;
        cin >> nodes[j];

    }
    while (nodes[j] != -1);

or

int j=0;
        do{

            cin >> nodes[j];

        }
        while (nodes[j++] != -1);

or

int j=0;
while(cin>>nodes[j] && nodes[j]!=-1)
{
     j++;
}