mastbaum

#include<iostream>
#include<vector>

/** There are two ways to access the ith element of an STL vector, the usual
 *  v[i] syntax or using v.at(i).
 *  
 *  The former doesn't check array boundaries, so something like v[v.size()+1]
 *  works and gives you whatever happens to be sitting in that memory location.
 *
 *  v.at() has the same purpose, but actually throws an exception

mastbaum

/** A simple example of an invalid pointer dereference.
 *  
 *  a is not a valid pointer until initialized, so dereferencing it (here,
 *  setting it to 37) is bad news.
 *
 *  Note that C++ doesn't necessarily initialize pointers to NULL, so it is
 *  possible that this will "work" and not cause a segmentation fault. This
 *  could be really bad, trampling some other memory. We're lucky to get a
 *  segfault.
 */

mastbaum

#include<iostream>
#include<vector>

/** Attention pointer lovers! You can declare C-style arrays as pointers and
 *  assign them to the reference returned by "new"ing a normal C array.
 *
 *  But don't. Please.
 */

int main()

mastbaum

#include<iostream>

/** C++ does some strange stuff with constructors. Having default values makes
 *  sense, but they've added some weird, unintuitive shorthand that's just an
 *  accident waiting to happen:
 *  
 *    MyClass c = MyClass(5) <--> MyClass c = 5
 *
 *  where in both cases 5 is taken as the first argument. In both cases, it will
 *  do whatever casting is needed and allowed.

mastbaum

#include<iostream>
#include<signal.h>
#include<limits.h>

/** g++'s -ftrapv flag provides some protection against integer overflows. It
 *  is a little awkward to use, though. All it will do is "trap" -- you must
 *  provide a signal handler to deal with it.
 *
 *  (You must compile with -ftrapv for this to work)
 */

mastbaum

#include<iostream>
#include<vector>
#include<stdlib.h>

/** People sometimes get the false impression that because STL and iterators
 *  are fairly new additions to C++, they do sensible, commonplace things like
 *  bounds checking.
 *
 *  This is sadly not the case, since preserving backwards-compatibility with C
 *  means preserving the loaded-gun-pointed-at-your-foot aspects, too.

mastbaum

#include<iostream>
#include<vector>

/** The name of std::vector::at makes it sound like it's a "getter" only.
 *  Can I set "v.at(i) = a" like I would "v[i] = a" ?
 *
 *  Yes.
 */

int main()

mastbaum

setenv PATH /usr/local/gcc44:/usr/local/scons-1.2.0/build/scripts:${PATH}
source /proj/common/sw/geant4/9.3.p01/env.csh > /dev/null
setenv ROOTSYS /proj/common/sw/root/5.26.00b
setenv PATH /proj/common/sw/root/5.26.00b/bin:${PATH}
if ( ${?LD_LIBRARY_PATH} )  then
setenv LD_LIBRARY_PATH /proj/common/sw/clhep/2.0.4.5/lib:/proj/common/sw/root/5.26.00b/lib:${LD_LIBRARY_PATH}
else
setenv LD_LIBRARY_PATH /proj/common/sw/clhep/2.0.4.5/lib:/proj/common/sw/root/5.26.00b/lib
endif
if ( ${?DYLD_LIBRARY_PATH} )  then

mastbaum

#include<stdio.h>
#include<malloc.h>

typedef struct
{
    unsigned long a;
} Bar;

typedef struct
{

mastbaum

#include<stdio.h>
#include<malloc.h>

typedef struct
{
    unsigned long a;
} Bar;

typedef struct
{