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++; }