bug1556.cpp

1     #include <stdio.h>
2
3     int *array(int n)
4         {
5         return new int(n);
6         }
7
8     int main()
9         {
10        int *p = array(10);
11        for( int i = 0; i < 10; i++ )
12            {
13            p[i] = 0;
14            }
15        printf( "%d\n", p[0] );
16        p = array(10);
17        printf( "%d\n", p[0] );
18        return 0;
19        }

This program is producing strange results. With one compiler I get a report that it has performed an illegal operation. With another compiler I get no output. What's going on?

bug1556.cpp lint Output

--- Module:   bug1556.cpp
                    _
    return new int(n);
bug1556.cpp(5) : Warning 1556: 'new Type(integer)' is suspicious

Reference Manual Explanation

 
1556  'new Type(integer)' is suspicious  -- A new expression had
      the form new T(Integer) where type T has no constructor.
      For example:

                new int(10);

      will draw this warning.  The expression allocates an area
      of storage large enough to hold one integer.  It then
      initializes that integer to the value 10.  Could this have
      been a botched attempt to allocate an array of 10
      integers?  Even if it was a deliberate attempt to allocate
      and initialize a single integer, a casual inspection of
      the code could easily lead a reader astray.

      The warning is only given when the type T has no
      constructor.  If T has a constructor then either a
      syntactic error will result because no constructor matches
      the argument or a match will be found.  In the latter case
      no warning will or should be issued.