Building a dynamic SQL query - c++

Question

I want to read value from the user and use it in my select query. How can I use a dynamic value in the SQL query?
My current code gives me this error:
ORA-01002: fetch out of sequence
This is my code:
void buildQuery()
{
cout << "Enter flight no :";
cin >> value;
strcpy((char *)sql_statement.arr,"select fname from flights where
flno = " + value );
cout << "Query is " << (char *) sql_statement.arr<< endl;
}
void executeQuery()
{
sql_statement.len = strlen((char *) sql_statement.arr);
exec sql PREPARE S1 FROM :sql_statement;
exec sql declare C1 cursor FOR S1;
exec sql open C1 ;
while(1)
{
exec sql FETCH C1 INTO :fname;
if ( sqlca.sqlcode != 0)
{
cout << "past fetch..." <<endl;
break;
}
cout << "Employee Name is: = " << (char *)ename.arr << endl;
}
exec sql close C1;
}