I'm trying to get Intel C++ 14.0.2 compiler to use the C++11 options. I've got this really simple code (which I simplified from: cplusplus.com):
// shared_ptr constructor example
#include <iostream>
#include <memory>
struct C {int* data;};
int main () {
std::shared_ptr<int> p1;
std::cout << "use_count:\n";
std::cout << "p1: " << p1.use_count() << '\n';
return 0;
}
I tried to compile this with the Intel C++ 14.0.2 compiler but I just get these errors:
$ icpc --std=c++11 test.cpp
test.cpp(8): error: namespace "std" has no member "shared_ptr"
std::shared_ptr<int> p1;
^
test.cpp(8): error: type name is not allowed
std::shared_ptr<int> p1;
^
test.cpp(8): error: identifier "p1" is undefined
std::shared_ptr<int> p1;
^
compilation aborted for test.cpp (code 2)
(I've also tried using -std=c++11, but got the same errors.) Am I using the shared_ptr wrong? Am I invoking the compiler wrong? This seems to be about as simple an example as I can come up with to illustrate this problem.
shared_ptr isn't listed as one of the supported features for version 14.0 in Intel's list of supported features:
http://software.intel.com/en-us/articles/c0x-features-supported-by-intel-c-compiler
Related
I'm new to c++ and have taken the liberty to learn it this summer after coming from a python background. I was watching a video about how to create and use tuples within c++ and it seemed to have worked for the YouTuber, however when I replicated his steps, my compiler had thrown some errors even though there was no distinct differences in the code
code:
#include <iostream>
#include <string>
#include <tuple>
int main() {
std::tuple <int, std::string> person(18, "Chris");
std::cout << std::get<1>(person) << std::endl;
return 0;
}
Errors:
❯ g++ -o main Tuples.cpp && ./main
Tuples.cpp:7:10: error: no member named 'tuple' in namespace 'std'
std::tuple <int, std::string> person(18, "Chris");
~~~~~^
Tuples.cpp:7:20: error: expected '(' for function-style cast or type construction
std::tuple <int, std::string> person(18, "Chris");
~~~^
Tuples.cpp:8:30: error: use of undeclared identifier 'person'
std::cout << std::get<1>(person) << std::endl;
^
3 errors generated.
Video for reference: https://www.youtube.com/watch?v=T9-agjKW4PQ&list=PLzMcBGfZo4-lmGC8VW0iu6qfMHjy7gLQ3&index=16
Given the following source code:
#include <memory>
#include <typeinfo>
struct Base {
virtual ~Base();
};
struct Derived : Base { };
int main() {
std::unique_ptr<Base> ptr_foo = std::make_unique<Derived>();
typeid(*ptr_foo).name();
return 0;
}
and compiled it with:
clang++ -std=c++14 -Wall -Wextra -Werror -Wpedantic -g -o test test.cpp
Enviroment setup:
linux x86_64
clang version 5.0.0
It does not compile because of warning (note -Werror):
error: expression with side effects will be evaluated
despite being used as an operand to 'typeid'
[-Werror,-Wpotentially-evaluated-expression]
typeid(*ptr_foo).name();
(Just a note: GCC does not claim that kind of potential problematic)
Question
Is there a way to get the information about the type pointed by a unique_ptr without generating that kind of warning?
Note: I am not talking about disabling -Wpotentially-evaluated-expression or avoiding -Werror.
Looks like following should work without warnings and give correct result for derived class
std::unique_ptr<Foo> ptr_foo = std::make_unique<Bar>();
if(ptr_foo.get()){
auto& r = *ptr_foo.get();
std::cout << typeid(r).name() << '\n';
}
I'm trying to compile a simple program utilizing literals from the std::literals namespace, but Clang is generating errors when I try to compile it.
The code I'm trying to compile:
#include <string>
#include <iostream>
using namespace std::literals;
int main()
{
std::cout << "Hello World!"s << std::endl;
return 0;
}
and the compilation command:
clang++ -stdlib=libstdc++ -std=c++1y a.cpp
which leads to this output:
a.cpp:4:22: error: expected namespace name
using namespace std::literals;
~~~~~^
a.cpp:8:29: error: no matching literal operator for call to 'operator "" s' with arguments of
types 'const char *' and 'unsigned long', and no matching literal operator template
std::cout << "Hello World!"s << std::endl;
^
2 errors generated.
Using g++ or libc++ are out of the question for various reasons, and I've confirmed that other C++14 features (ie. return type deduction and binary literals) work, so it's not an issue with the compiler, making me believe it involves libstdc++.
What can I do to fix this? I'm on Linux Mint 17.1 if it makes any difference.
Remember to ensure that you're compiling the source according to C++14 (the chrono literals are not provided in C++11).
clang++ -stdlib=libstdc++ -std=c++14 a.cpp
I've been learning C++ and using the Terminal for the last couple of months. My code was compiling and running fine using g++ and C++11, but in the last couple of days it started giving errors and I have had problems compiling since. The only programs I can compile and run depend on older C++ standards.
The errors I first got related to #include < array > in the header file. Not sure why this happened, but I got around it by using boost/array instead. Another error I can't solve is with std::stoi. Both array and stoi should be in the C++11 standard library. I made the following simple code to demonstrate what's going on:
//
// stoi_test.cpp
//
// Created by ecg
//
#include <iostream>
#include <string> // stoi should be in here
int main() {
std::string test = "12345";
int myint = std::stoi(test); // using stoi, specifying in standard library
std::cout << myint << '\n'; // printing the integer
return(0);
}
Try to compile using ecg$ g++ -o stoi_trial stoi_trial.cpp -std=c++11
array.cpp:13:22: error: no member named 'stoi' in namespace 'std'; did you mean
'atoi'?
int myint = std::stoi(test);
~~~~~^~~~
atoi
/usr/include/stdlib.h:149:6: note: 'atoi' declared here
int atoi(const char *);
^
array.cpp:13:27: error: no viable conversion from 'std::string' (aka
'basic_string') to 'const char *'
int myint = std::stoi(test);
^~~~
/usr/include/stdlib.h:149:23: note: passing argument to parameter here
int atoi(const char *);
^
2 errors generated.
I also get these errors at compilation when using gcc or clang++ and with -std=gnu++11 (I guess they all depend on the same file structure). I also get the same error whether I specify std:: in the code, or if I specify using namespace std;
I worry that these issues arose because of the September Command Line Tools update via Xcode or because I installed boost and this somehow messed up my C++11 libraries. Hopefully there is a simple solution.
My system:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-> dir=/usr/include/c++/4.2.1
Apple LLVM version 5.0 (clang-500.2.76) (based on LLVM 3.3svn)
Target: x86_64-apple-darwin12.5.0
Thread model: posix
Thanks for any insight you can offer.
clang has a weird stdlib, you need to add the following flag when you compile
-stdlib=libc++
your snippet works on my mac with
g++ -std=gnu++11 -stdlib=libc++ test.cpp -o test
This answer describes the problem
I am completely new to C++ and I am now following the C++ Primer book.
I wrote a small example about strings, here is the code:
#include <iostream>
#include <string>
#include <cctype>
using std::cin;
using std::cout;
using std::endl;
using std::string;
int main() {
string s("Hello World");
for (auto &c : s)
c = toupper(c);
cout << s << endl;
return 0;
}
I am on Linux with GCC version 4.4.6 and I tried to compile this code with:
g++ test_strings.c -std=c++0x
but got the following errors:
test_strings.c: In function 'int main()':
test_strings.c:14: error: expected initializer before ':' token
test_strings.c:19: error: expected primary-expression before 'return'
test_strings.c:19: error: expected ')' before 'return'
I copied the program from the textbook, so I though it was a misspelling but after a check and trying searching on the web and updating my gcc the error reminds. Help will be greatly appreciated, thanks in advance.
As per the C++0x/C++11 Support in GCC page, you need to be running gcc 4.6 to get the range-for feature.
The 4.6 changes page contains:
Improved experimental support for the upcoming C++0x ISO C++ standard, including support for constexpr (thanks to Gabriel Dos Reis and Jason Merrill), nullptr (thanks to Magnus Fromreide), noexcept, unrestricted unions, range-based for loops (thanks to Rodrigo Rivas Costa), opaque enum declarations (thanks also to Rodrigo), implicitly deleted functions and implicit move constructors.
Since you're running gcc 4.4.6, it's not available to you.