Originally posted by: mido199

Hello, 

I am using CPLEX 12.8 to solve a MIP, howver I am getting a segmentation fault when I try to set the name of one of my variables. When I run valgrind, I get: Use of uninitialised value of size 8 at line written in bold in the code below, I run again Valgrind with --track-origins=yes, I get Uninitialised value was created by a heap allocation. Do I need to initialize variables in CPLEX ? I really don't understand this error. 

    m = IloArray<IloArray<IloNumVarArray>>(env, (int)moves.size());

    for(int l=0; l<moves.size(); l++)
    {
        printf("l: %d \n",l);
        MoveConfig<Node,Driver,MoveAgv> mo = moves[l];
        m[mo.config_index] = IloArray<IloNumVarArray>(env,  mo.NbrOfNodes );

            for(int i = mo.start_node_pos; i<mo.start_node_pos + mo.NbrOfNodes; i++)
            {
                Node * n = request_to_insert->GetNode(i);             
                m[mo.config_index][n->no] = IloNumVarArray(env, 1, 0, 1, ILOINT);             
                char name[40];
                sprintf(name,"m%d_%d_%d",mo.config_index,n->no,mo.move.prev->no);
                m[mo.config_index][n->no][mo.move.prev->no].setName(name);
    
            }    
        
    }

Originally posted by: T_O

Might it be that for some reason, n->no is not initialized?

Originally posted by: mido199

Hello T_O, 

Thank you for your answer. I printed out the content of mo.config_index and n->no, it was displayed correctly. It is a strange error !!! 

Originally posted by: T_O

Ok. Let's for a while forget about the valgrind problem.

Did you try to use a debugger to find out where exactly the segmentation fault occurs? (This is not necessarily the same line as your valgrind problem. Maybe something like mo.move.prev->no is missing.)

Originally posted by: mido199

Yes I tried with GDB, here is the output: 

Program received signal SIGSEGV, Segmentation fault.
0x0000555555619cab in ExactInsertMIP::Init (this=0x7fffffffd460, s=..., moves=std::vector of length 65, capacity 128 = {...})
    at ./Agv/ExactInsertMIP.cpp:120
120                    m[mo.config_index][n->no] = IloNumVarArray(env, 1, 0, 1, ILOINT);
 

note that, ExactInsertMIP::Init is the function where I build my MIP. according to gdb, the problem is in the line: m[mo.config_index][n->no] = IloNumVarArray(env, 1, 0, 1, ILOINT)

Originally posted by: T_O

Hmm, ok.

What is the value of mo.NbrOfNodes and what is the value of n->no when the segmentation fault occurs? Maybe, m[mo.config_index] is too short.

Originally posted by: mido199

Here are the values: 

mo.start_node_pos = 0

mo.NbrOfNodes = 1 

mo.config_index = 0

n->no = 130

mo.move.prev->no = 0 

Originally posted by: T_O

That's it.

m[mo.config_index] has a size of 1 (because of "m[mo.config_index] = IloArray<IloNumVarArray>(env,  mo.NbrOfNodes )").

Then you cannot write to index 130 (m[mo.config_index][n->no]).

Originally posted by: mido199

Yeah , you are right, I also realized it when you asked me the question about the values. Thank you so much for the help.