Re: declare a struct with c++ vectors in a header file...
* beet:
On Jun 16, 11:28 pm, "Alf P. Steinbach" <al...@start.no> wrote:
* Eric Pruneau:
* "beet" <whh...@gmail.com>:
I tried to declare a c++ struct like following in a header file:
------
1 #ifndef _SEARCHDATA_H_
2 #define _SEARCHDATA_H_
Never define names starting with underscore followed by uppercase letter.
Those are reserved for the C++ implementation.
That also goes for use of double underscore.
3
4 #include <vector>
5 #include <list>
6
add :
using namespace std;
or you gonna have to be type 'std::vector' instead of just 'vector'.
vector (list too) is a class inside the namespace std.
I'm sorry, but that is extremely bad advice.
Never add "using namespace std;" in a header file. It will force unqualified
names from the standard library, on all code that uses the header file. And in
particular, "string" and "vector" are commonly used names for other things than
the standard library classes, and you really don't want to screw up things for
code that uses those names -- that's why the standard library uses "std::".
Conversely, when you see "using namespace std;" in a header file then you know
that the author is incompetent or an utter novice.
Cheers, & hth.,
- Alf
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Please don't quote signatures.
Thanks for your replies...
I modified a bit my code according to your comments, but it seems
problems with declaration of functions:
g++ -Wall -g -c searchData.cpp
searchData.cpp: In function `int searchPt(std::vector<int,
std::allocator<int> >&, searchIter&, double&, double&)':
searchData.cpp:46: warning: comparison between signed and unsigned
integer expressions
This is from code you haven't shown. It's just a warning but you should fix it.
Typical fix to is use 'size_t' for a loop variable.
g++ -Wall -g -o runinv functionfile.o retroSearch.o searchData.o
simlib.o myinv.o mxCalc.o optSolver.o
optSolver.o(.text+0x1d27): In function `egSearch(std::vector<double,
std::allocator<double> >&, double, float&, double&, searchIterInfo&,
float)':
/home/wang75/myResearch/generic/simContSearch/optSolver.cpp:351:
undefined reference to `getInitStep(std::vector<double,
std::allocator<double> > const&, std::vector<double,
std::allocator<double> >&, int, float, int)'
This an undefined reference because the message says "undefined reference".
That means the object files you're linking don't have an implementation of that
function.
Probably it's due to a signature mismatch for something you think is an
implementation.
optSolver.o(.text+0x1ffb):/home/wang75/myResearch/generic/
simContSearch/optSolver.cpp:382: undefined reference to
`getInitStep(std::vector<double, std::allocator<double> > const&,
std::vector<double, std::allocator<double> >&, int, float, int)'
optSolver.o(.text+0x4039): In function `fcn(std::vector<double,
std::allocator<double> > const&, std::vector<double,
std::allocator<double> >&, double, searchIterInfo&, int, int, float)':
/home/wang75/myResearch/generic/simContSearch/optSolver.cpp:711:
undefined reference to `simplexInterp(std::vector<double,
"undefined reference"
std::allocator<double> > const&, std::vector<std::vector<int,
std::allocator<int> >, std::allocator<std::vector<int,
std::allocator<int> > > >&, std::vector<double, std::allocator<double>
&, std::vector<int, std::allocator<int> >&, int, float, int)'
optSolver.o(.text+0x465c): In function `fcnPart(std::vector<double,
std::allocator<double> > const&, std::vector<double,
std::allocator<double> >&, double, int, searchIterInfo&, int, int,
float)':
/home/wang75/myResearch/generic/simContSearch/optSolver.cpp:768:
undefined reference to `simplexInterp(std::vector<double,
"undefined reference"
std::allocator<double> > const&, std::vector<std::vector<int,
std::allocator<int> >, std::allocator<std::vector<int,
std::allocator<int> > > >&, std::vector<double, std::allocator<double>
&, std::vector<int, std::allocator<int> >&, int, float, int)'
collect2: ld returned 1 exit status
make: *** [runinv] Error 1
shell returned 2
----my code ---
1 #ifndef _searchData_
2 #define _searchData_
Generally only use ALL UPPERCASE for macro names, and never use that convention
for other names, so as to avoid possible name collisions (macros don't respect
scopes) -- this is a FAQ.
I should have been less specific about underscore advice.
As a rule, never use any leading underscore whatsoever, because in the global
namespace those names are reserved for the implementation, and it's easiest to
just never use them rather than remember where they're not reserved.
3 #include <vector>
4 #include <list>
5
6 typedef struct searchIterInfo {
This is a C-ism, not necessary in C++. The C construct
typedef struct { blah blah } SomeName;
is, in C++, better expressed as
struct SomeName { blah blah };
7 searchIterInfo ():
8 contPts(0), //continuous trial points
9 contFvs(0), //fv for cont points
10 contFerrors(0), //std errors for cont points
11 gradients(0), //list of gradients
12 intPts(0), //evaluated int points
13 intFvs(0), //function values for int points
14 intFerrors(0), //errors for int points
15 intPtList(0), //the monotone list of points
16 simList(0), //the simplex list
17 seedVals(0), //the seed values
18 hMtx(0) {}; //the estimated hesian matrix
Extraneous semicolon after right brace.
Anyway you don't need to define the vector initializations because they're what
you get by default. :-)
What you do need to initialize is what you've forgotten to initialize, namely
the members of built-in type 'iterID' and 'sampleSize': since they're not of
class type they don't have automatic default initialization.
19
20 std::vector< std::vector<double> > contPts;
21 std::vector<double> contFvs;
22 std::vector<double> contFerrors;
23 std::vector< std::vector<double> > gradients;
24 std::vector< std::vector<int> > intPts;
25 std::vector<double> intFvs;
26 std::vector<double> intFerrors;
27 std::list<int> intPtList;
28 std::list<int> simList;
29 std::vector<int> seedVals;
30 std::vector< std::vector<double> > hMtx;
31 int iterID; //the sample path index
32 double sampleSize; //the sample size for this sp
Since the above doesn't communicate any purpose to me, it probably will not
communicate any purpose to you either when you have been away from the code for
some time. So better more self-describing names would probably be a good idea.
It's also possible, but by no means sure, that you're doing an unnecessary
inversion of data structure, using a struct of vectors when problem domain calls
for a vector of structs -- generally a struct of like vectors indicate that. :-)
33 } searchIter;
34
35 std::vector<int> getBestIntPt(searchIter &);
36 int searchPt(std::vector<int> &, searchIter &, double &,
double &);
37 void addPt(std::vector<int> &, searchIter &, double fv, double
fr);
38
39 #endif
Cheers, & hth.,
- Alf
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?