Subject: RE: STL iterators in gcc 3.2 - msg#00320

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RE: STL iterators in gcc 3.2

> > 1.- Whereas I didn't need it before, now I have to use the "using > namespace std" directive if I want to use cout, cin,... and all this > stuff. Why the change? > This version of gcc (and g++) is more standards compliant, hence the new necessity of std:: when using the iostreams and other standard library features. > 2.- This is more serious. In my programs I use a lot of STL > vectors, and > so, iterators too. When I had a method with a pointer > argument, I passed a > random iterator to it. It worked fine with previous versions > of gcc, but > not with 3.2. Is there any way to get it work or do I have to > come back to > an older version? > >From what I've noticed, the old 2.95 implemented std::vector iterators as just plain pointers (|std::vector<double>| used |double*|'s for iteration). It looks like now the library is using class abstractions for its iterators. This has many benefits, but it also means that some code, e.g., void foo(double*); std::vector<double> myvect; foo(myvect.begin()); will no longer work, since |myvect.begin()| does not necessarily produce a double*. I have found in order to make your code independent of the iterator object, you have to either use templates, template <typename OutputIterator> void foo(OutputIterator); or you must specifically use the iterator type defined by your container, void foo(std::vector<double>::iterator); I don't know if there is an easier conversion than either of these, but I would be interested in hearing any other ideas. --Matt

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Problems with stringstream

Hi, I'm trying to build the following program using gcc 3.0.3. It compiles okay but when it runs there is no output. When I compile and run on MS Visual C++ the output is "Sample string" as expected. I did a quick check of the FAQ for this topic but couldn't find any information. Any suggestions are appreciated! #include <iostream> #include <sstream> #include <string> using namespace std; int main () { stringstream oss; string mystr; oss << "Sample string"; mystr=oss.str(); cout << mystr; return 0; } Thanks, Mark

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RE: STL iterators in gcc 3.2

> > 1.- Whereas I didn't need it before, now I have to use the "using > namespace std" directive if I want to use cout, cin,... and all this > stuff. Why the change? > This version of gcc (and g++) is more standards compliant, hence the new necessity of std:: when using the iostreams and other standard library features. > 2.- This is more serious. In my programs I use a lot of STL > vectors, and > so, iterators too. When I had a method with a pointer > argument, I passed a > random iterator to it. It worked fine with previous versions > of gcc, but > not with 3.2. Is there any way to get it work or do I have to > come back to > an older version? > >From what I've noticed, the old 2.95 implemented std::vector iterators as just plain pointers (|std::vector<double>| used |double*|'s for iteration). It looks like now the library is using class abstractions for its iterators. This has many benefits, but it also means that some code, e.g., void foo(double*); std::vector<double> myvect; foo(myvect.begin()); will no longer work, since |myvect.begin()| does not necessarily produce a double*. I have found in order to make your code independent of the iterator object, you have to either use templates, template <typename OutputIterator> void foo(OutputIterator); or you must specifically use the iterator type defined by your container, void foo(std::vector<double>::iterator); I don't know if there is an easier conversion than either of these, but I would be interested in hearing any other ideas. --Matt

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Problems with stringstream

Hi, I'm trying to build the following program using gcc 3.0.3. It compiles okay but when it runs there is no output. When I compile and run on MS Visual C++ the output is "Sample string" as expected. I did a quick check of the FAQ for this topic but couldn't find any information. Any suggestions are appreciated! #include <iostream> #include <sstream> #include <string> using namespace std; int main () { stringstream oss; string mystr; oss << "Sample string"; mystr=oss.str(); cout << mystr; return 0; } Thanks, Mark