When i try to compile the following code:
#include <string.h>
using namespace std;
typedef std::basic_string<char> foostring;
foostring foo = "foo";
I get the following error:
stringtest.cpp:5: error: expected initializer before ‘<’ token
stringtest.cpp:6: error: ‘foostring’ does not name a type
My compiler is: g++ (Ubuntu 4.4.1-4ubuntu9) 4.4.1
What am i doing wrong? i intend to use this with windows TCHAR for unicode support once i figure out how to use it.
The header is <string>, not <string.h>.
None of the standard library headers end with an extension. (You're including the C header string.h, which should be included in C++ via <cstring>, had that been what you actually wanted.)
Related
I like to create a TUN/TAP interface out of a C++ program. I found a straight foward tutorial on the net at
http://backreference.org/2010/03/26/tuntap-interface-tutorial/.
The problem is, that I seem to have linking problems with with if.h and if_tun.h.
When I strip the tutorial to the minimal example below, only to open a slot, I get a number of errors.
Example:
#include <linux/if.h>
#include <linux/if_tun.h>
int main(void){
char *clonedev = "/dev/net/tun";
open(clonedev,O_RDWR);
return 0;
}
If think this should compile, yet I get the following errors:
/usr/include/linux/if.h:184:19: error: field 'ifru_addr' has incomplete type
/usr/include/linux/if.h:185:19: error: field 'ifru_dstaddr' has incomplete type
/usr/include/linux/if.h:186:19: error: field 'ifru_broadaddr' has incomplete type
/usr/include/linux/if.h:187:19: error: field 'ifru_netmask' has incomplete type
/usr/include/linux/if.h:188:20: error: field 'ifru_hwaddr' has incomplete type
tuntap.cpp: In function 'int main()':
tuntap.cpp:6:18: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
tuntap.cpp:7:15: error: 'O_RDWR' was not declared in this scope
tuntap.cpp:7:21: error: 'open' was not declared in this scope
I'm using GCC 4.7.2 (in this case, from the command line without any switches) on Fedora 18 with Linux 3.11.4.
What's wrong with my libraries?
Try a different include. Use ...
#include <net/if.h>
... instead of ...
#include <linux/if.h>
In addition, include another file.
#include <fcntl.h>
I am developing a program in C++ on Linux. The gcc version is 4.5.1 20100924. I want to use std::atomic_int in my program. I have included atomic header as below:
include <atomic>
When I compile the program I get below errors:
In file included from /usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomic_base.h:87:0,
from /usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/atomic:41,
from ../Source/Main.h:33:
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomicfwd_cxx.h:107:25: error: ‘char16_t’ was not declared in this scope
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomicfwd_cxx.h:107:33: error: template argument 1 is invalid
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomicfwd_cxx.h:107:53: error: invalid type in declaration before ‘;’ token
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomicfwd_cxx.h:110:25: error: ‘char32_t’ was not declared in this scope
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomicfwd_cxx.h:110:33: error: template argument 1 is invalid
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/atomicfwd_cxx.h:110:53: error: invalid type in declaration before ‘;’ token
If I include <cstdint>, I get the same errors. The headers uchar.h and cuchar.h are not there on my system. How can I resolve the compilation errors?
Thank you in advance.
EDITED:
I was wrong about that. just pass --std=c++0x to g++, and that would do it.
You seem to not have enabled C++11 support in your compiler or you use a compiler that has these new types not declared.
For char16_t and char32_t, you need no extra include.
g++ howto:
Type g++ --version. If it is at least 4.4, then it has support for new string literals. If not: You need a newer compiler version.
Then, make sure to pass --std=c++0x or --std=c++11 to the compiler.
I am trying to run an old C++ code in Linux (Redhat). I am using gcc version 4.1.2.
I got the following error:
error: strstream.h: No such file or directory
/trnuser1/rmtrain/DevelopmentEnv/Generic/CoreObjects/GCVTransformationServices.cpp:41: error: âostrstreamâ was not declared in this scope
/trnuser1/rmtrain/DevelopmentEnv/Generic/CoreObjects/GCVTransformationServices.cpp:41: error: expected `;' before âstrDestXMLâ
/trnuser1/rmtrain/DevelopmentEnv/Generic/CoreObjects/GCVTransformationServices.cpp:62: error: âstrDestXMLâ was not declared in this scope
This code was running fine under Solaris with gcc version 2.95. The line pointed to by the error contains the following statement:
ostrstream strDestXML;
How do I solve this?
You can #include <strstream> (note absence of the '.h' suffix).
But if you want to properly port the code to modern C++, you should consider changing this to #include <sstream> and std::ostringstream strDestXML; as suggested in the comment.
Standard C++ headers do not have extension.
#include <sstream>
Standard classes are contained in std namespace:
std::ostringstream strDestXML;
Finally, strstream is deprecated; use stringstream instead - that's why I used it here.
And, just a note about GCC version - 4.1.2 is old, no matter what - use something newer.
The modern name for this include is <strstream>. (Although it's formally deprecated, it's still required.) The classes it defines are in namespace std, and have slightly different semantics than the classical iostream, so you may have to do a little bit of modification later anyway. (Depending on how it is being used, it might make sense to change to <sstream>, replacing [io]strstream with std::[io]stringstream.)
I'm looking for an implementation of Hybrid Tree(not important), and find an "old" one here.
The author said they have tried this code on the SUN Sparc platform (running Solaris 2.6) and with gcc-2.8.1 compiler. And my environment is gcc version 4.4.3 (Ubuntu 10.10).
The problem is:
I run "make" with the makefile he provides, but it gives me lots of error message as follows:
g++ -c Node.C
g++ -c DataNode.C
In file included from DataNode.h:18,
from DataNode.C:17:
Query.h:9:20: error: vector.h: No such file or directory
Query.h:10:19: error: stack.h: No such file or directory
Query.h:13:22: error: function.h: No such file or directory
Query.h:14:22: error: iostream.h: No such file or directory
DataNode.C:283:8: warning: extra tokens at end of #endif directive
In file included from DataNode.h:18,
from DataNode.C:17:
Query.h:29: warning: ‘typedef’ was ignored in this declaration
Query.h:44: warning: ‘typedef’ was ignored in this declaration
Query.h:86: error: expected initializer before ‘<’ token
Query.h:118: error: ISO C++ forbids declaration of ‘PQ’ with no type
Query.h:118: error: expected ‘;’ before ‘*’ token
Query.h:122: error: ISO C++ forbids declaration of ‘PQ’ with no type
Query.h:122: error: expected ‘;’ before ‘*’ token
Query.h:126: error: ISO C++ forbids declaration of ‘PQ’ with no type
Query.h:126: error: expected ‘;’ before ‘*’ token
Query.h:135: error: expected initializer before ‘<’ token
DataNode.C: In member function ‘void DataNode::DisconnectBranch(int)’:
DataNode.C:80: error: ‘memmove’ was not declared in this scope
make: *** [DataNode.o] Error 1
I know I need to modify the souce code so as to agree with the morden compiler, such as change vector.h to vector. But I find it's just endless.
So my question is: is there any convienent method to run this program, no matter automatically converting this code to "modern-style" or using a standalone "old-style" compiler ?
Any suggestions?
===Update:===
Thank you all, I installed gcc2.8.1 in a different dir using --prefix=/usr/local/gcc-2.8.1 and modify the "makefile" to use this old-version gcc(/usr/local/gcc-2.8.1/bin/gcc). But when I run "make", it still gives me errors of not finding the headers:
/usr/local/gcc-2.8.1/bin/gcc -c DataNode.C
In file included from DataNode.h:18,
from DataNode.C:17:
Query.h:9: vector.h: No such file or directory
Query.h:10: stack.h: No such file or directory
Query.h:11: deque: No such file or directory
Query.h:12: algorithm: No such file or directory
Query.h:13: function.h: No such file or directory
Query.h:14: iostream.h: No such file or directory
make: *** [DataNode.o] Error 1
Then I tried to find these heads in /usr/local/gcc-2.8.1 using find /usr/local/gcc-2.8.1 -name "*vector*", but got nothing.
So where are these heads for the old-version gcc?
You can make a vertor.h yourself which includes vector. This way you can fix the incompatibilities noninvasively.
Edit:
You may also need to add a
using namespace std;
in the header file(s). This is
generally a bad idea but this is one situation where i'd do it anyway.
Once you get it working i would reccomend rewriting it to use the new style header files and namespaces.
Debian Lenny (oldstable) has gcc 3.4. This might have a better backward compatibility. Try to make compatibility headers for the rest of the issues and include them via an extra -I directory, e.g. a vector.h header file that includes vector.
Do yourself the favor and try not to touch the old code. It is easy to break legacy code in unforeseen ways.
You could try running the program on QEMU which supports Solaris 2.6. The only problem might be hunting for the install disc/image. Also, there are people that sells old Solaris boxes on eBay for cheap, you might be able to grab one.
GCC provides download for very old versions, you might be able to get better chance if you try older version of the compiler.
gcc has -fpermissive option: try it and see whether at least some errors disappear. Also: try making a single header file that will include all requisite headers with using directives. For example, make stdinc.h containing:
#include <vector>
#include <iostream>
#include <stack>
...
using std::vector;
using std::fstream;
...
Replace all mentions of legacy C++ header files with a single include of stdinc.h. Old C++ didn't have namespaces, so even if you replace individual directives with just using namespace std;, clashes are unlikely.
If the only thing is
#include <vector.h>
to
#include <vector>
using namespace std;
Why not try sed?
grep for all includes to see if there are other includes than the c++ headers. If not your lucky.
Another thing that is more tricky is that there is old code that relies on accessing data through iterators in a non-standard way. I saw that in a Doom map editor for linux. Then you may need to do manual stuff.
If I put #include <vector.h> in my source file, I get this warning:
make -f Makefile CFG=Debug
g++ -c -g -o "Debug/mynn.o" "mynn.cpp"
In file included from C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/backward/vector.h:59,
from mynn.h:7,
from mynn.cpp:1:
**C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header. Please consider using one of the 32 headers found in section 17.4.1.2 of the C++ standard. Examples include substituting the <X> header for the <X.h> header for C++ includes, or <iostream> instead of the deprecated header <iostream.h>. To disable this warning use -Wno-deprecated.**
g++ -g -o "Debug/mynn.exe" Debug/mynn.o
and if I just add regular #include <vector> (without .h, like the warning suggests), I get the following errors:
make -f Makefile CFG=Debug
g++ -c -g -o "Debug/mynn.o" "mynn.cpp"
In file included from mynn.cpp:1:
**mynn.h:12: error: ISO C++ forbids declaration of `vector' with no type
mynn.h:12: error: expected `;' before '<' token
mynn.h:13: error: `vector' has not been declared
mynn.h:13: error: expected `,' or `...' before '<' token
mynn.h:13: error: ISO C++ forbids declaration of `parameter' with no type
mynn.h:20: error: ISO C++ forbids declaration of `vector' with no type
mynn.h:20: error: expected `;' before '<' token
mynn.h:21: error: ISO C++ forbids declaration of `vector' with no type
mynn.h:21: error: expected `;' before '<' token**
Is there a better way to include the vector header this so that it doesn't complain? Here's the source file that generates the warnings/errors:
// mynn.h
#ifndef _MYNN_H_
#define _MYNN_H_
#include <stdio.h>
#include <iostream>
#include <math.h>
#include <vector>
class neuron {
public:
neuron();
vector<int> weights;
int compute_sum (vector <int> &input);
};
class layer
{
public:
layer();
vector <neuron> nrns;
vector<int> compute_layer (vector <int> &input);
};
#endif /*_MYNN_H_*/
The problem is that vector<T> lives in the std namespace and you're attempting to use the type without any qualification or appropriate using statement. The safest fix is to explicitly qualify uses of the type with the std prefix.
std::vector<neuron> nrns;
This can also be fixed by explicitly importing the type via a using statement.
using std::vector;
I would avoid this approach though. Adding using statements to header files, while legal, is bad practice because it can change how items are compiled. This form safer than a blanket import of std but is still not great.
vector belongs to std namespace. You need to fully qualify its name as std::vector<int>.
I need to clarify that the C++ Standard allows you to use all options that JaredPar gave in his answer, but I would strongly recommend not to use using namespace std and especially in the header files. About using namespace std you can find well described opinion in this question. Personally I'm agree with it, so allow me to link it in my answer.
Indeed,
you need to specify std::vector as vector is not global.
But I would rather advice you to NOT use using keyword.
The problem is the scope of the using, and the conflicts that could raise after.
MOREOVER if you're planning to have a portable apps (code), (especially for library) you should avoid sush a thing because you can't be sure of the side effects on other plateforms, for the future users of your code.