Error begin was not declared in this scope

I’m trying to learn c++, so I wrote a short program that uses the new c++11 for loop, which makes the compiler give me an error I don’t understand.
this is my c++ code:

#include <iostream>
#include <cmath>
using namespace std;

float legge_oraria_moto_accelerato(float a[3]){
    return a[2]*a[0] + 0.5*a[1]*a[0]*a[0];
}
int corri(float (f)(float array[3]), float arrays[3][3])
    { for(auto i:arrays) cout << f(i) << 'n';
    return 0;
} 

int main()
{ 
return 0;
}

and this is the compiler’s (g++ -std=gnu++11) error:

mezzo.cpp: In function ‘int corri(float (*)(float*), float (*)[3])’:
mezzo.cpp:9:18: error: ‘begin’ was not declared in this scope
     { for(auto i:arrays) cout << f(i) << 'n';
                  ^
mezzo.cpp:9:18: note: suggested alternatives:
In file included from /usr/include/c++/4.9/bits/basic_string.h:42:0,
                 from /usr/include/c++/4.9/string:52,
                 from /usr/include/c++/4.9/bits/locale_classes.h:40,
                 from /usr/include/c++/4.9/bits/ios_base.h:41,
                 from /usr/include/c++/4.9/ios:42,
                 from /usr/include/c++/4.9/ostream:38,
                 from /usr/include/c++/4.9/iostream:39,
                 from mezzo.cpp:1:
/usr/include/c++/4.9/initializer_list:89:5: note:   ‘std::begin’
     begin(initializer_list<_Tp> __ils) noexcept
     ^
/usr/include/c++/4.9/initializer_list:89:5: note:   ‘std::begin’
mezzo.cpp:9:18: error: ‘end’ was not declared in this scope
     { for(auto i:arrays) cout << f(i) << 'n';
                  ^
mezzo.cpp:9:18: note: suggested alternatives:
In file included from /usr/include/c++/4.9/bits/basic_string.h:42:0,
                 from /usr/include/c++/4.9/string:52,
                 from /usr/include/c++/4.9/bits/locale_classes.h:40,
                 from /usr/include/c++/4.9/bits/ios_base.h:41,
                 from /usr/include/c++/4.9/ios:42,
                 from /usr/include/c++/4.9/ostream:38,
                 from /usr/include/c++/4.9/iostream:39,
                 from mezzo.cpp:1:
/usr/include/c++/4.9/initializer_list:99:5: note:   ‘std::end’
     end(initializer_list<_Tp> __ils) noexcept
     ^
/usr/include/c++/4.9/initializer_list:99:5: note:   ‘std::end’

Hi, newbie here. I’m playing around with programming by using an Arduino to control ARGB lighting strips.

I have the following function:

void Fade_multi (int sleds[], int steps, int speed, int red, int green, int blue) {
    for (int st = 0; st < steps; st++) {
      for (int x : sleds) {
        if (sleds [st] = 1) {
            Fade_steps(steps,speed,x,x,red,green,blue);
        }
      }
    }
}

When I compile my code, I get the following error:

'begin' was not declared in this scope

I assume that the error is related to the function I am calling in this function, which is:

void Fade_steps(int steps, int speed, int begin, int end, int red, int green, int blue) {
  for (int s = 0; s < steps; s++) {
    for (int v = 0; v < speed; v++) {
      Fade_one_step_to_colour(begin, end, red, green, blue);
    }
  FastLED.delay(1);
  }
}

This piece of code hasn’t caused issues with compiling itself — when I comment the Fade_multi function out it compiles without issue.

I think this might have something to do with the variable begin not being declared in Fade_multi, but I’m also not calling it there. So I am a bit confused as to the cause of this error.

Edit: full code: https://pastebin.com/ffXkuD9u

🐛 Bug

The example for ModuleList found in the documentation here does not seem to compile.

To Reproduce

Steps to reproduce the behavior:

Attempt to compile the following source on GCC 7.4, taken from the documentation:

#include <torch/torch.h>

int main() {

  torch::nn::ModuleList mlist(
    torch::nn::Linear(3, 4),
    torch::nn::BatchNorm(4),
    torch::nn::Dropout(0.5)
  );

  for (const auto &module : mlist) {
    module.pretty_print();
}

Compile error:

C++ compilation of rule '//src/learning:pytorch' failed (Exit 1) gcc failed: error executing command /usr
/bin/gcc -U_FORTIFY_SOURCE -fstack-protector -Wall -Wunused-but-set-parameter -Wno-free-nonheap-object -fno-omit-frame-pointer -g0 -O2 '-D_FORTIFY_SOURCE=1' -DNDEBUG -ffunction-sections ... (remaining 38 argument(s) skipped)

Use --sandbox_debug to see verbose messages from the sandbox
src/learning/pytorch_test.cpp: In function 'int main()':
src/learning/pytorch_test.cpp:12:29: error: 'begin' was not declared in this scope
   for (const auto &module : mlist) {
                             ^~~~~
src/learning/pytorch_test.cpp:12:29: note: suggested alternative:
In file included from /usr/include/c++/7/string:51:0,
                 from /usr/include/c++/7/stdexcept:39,
                 from /usr/include/c++/7/array:39,
                 from /usr/include/c++/7/tuple:39,
                 from /usr/include/c++/7/bits/unique_ptr.h:37,
                 from /usr/include/c++/7/memory:80,
                 from external/pytorch/libtorch/include/c10/core/Allocator.h:4,
                 from external/pytorch/libtorch/include/ATen/ATen.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/types.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader_options.h:4,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader/base.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader/stateful.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/all.h:4,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/torch.h:3,
                 from src/learning/pytorch_test.cpp:1:
/usr/include/c++/7/bits/range_access.h:105:37: note:   'std::begin'
   template<typename _Tp> const _Tp* begin(const valarray<_Tp>&);
                                     ^~~~~
src/learning/pytorch_test.cpp:12:29: error: 'end' was not declared in this scope
   for (const auto &module : mlist) {
                             ^~~~~
src/learning/pytorch_test.cpp:12:29: note: suggested alternatives:
In file included from /usr/include/c++/7/string:51:0,
                 from /usr/include/c++/7/stdexcept:39,
                 from /usr/include/c++/7/array:39,
                 from /usr/include/c++/7/tuple:39,
                 from /usr/include/c++/7/bits/unique_ptr.h:37,
                 from /usr/include/c++/7/memory:80,
                 from external/pytorch/libtorch/include/c10/core/Allocator.h:4,
                 from external/pytorch/libtorch/include/ATen/ATen.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/types.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader_options.h:4,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader/base.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader/stateful.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/all.h:4,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/torch.h:3,
                 from src/learning/pytorch_test.cpp:1:
/usr/include/c++/7/bits/range_access.h:107:37: note:   'std::end'
   template<typename _Tp> const _Tp* end(const valarray<_Tp>&);
                                     ^~~
In file included from external/pytorch/libtorch/include/ATen/core/Dimname.h:5:0,
                 from external/pytorch/libtorch/include/ATen/core/NamedTensor.h:4,
                 from external/pytorch/libtorch/include/ATen/core/TensorBody.h:20,
                 from external/pytorch/libtorch/include/ATen/Tensor.h:11,
                 from external/pytorch/libtorch/include/ATen/Context.h:4,
                 from external/pytorch/libtorch/include/ATen/ATen.h:5,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/types.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader_options.h:4,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader/base.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader/stateful.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data/dataloader.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/data.h:3,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/all.h:4,
                 from external/pytorch/libtorch/include/torch/csrc/api/include/torch/torch.h:3,
                 from src/learning/pytorch_test.cpp:1:
external/pytorch/libtorch/include/ATen/core/interned_strings.h:374:1: note:   'c10::attr::end'
 FORALL_NS_SYMBOLS(DEFINE_SYMBOL)
 ^
external/pytorch/libtorch/include/ATen/core/interned_strings.h:374:1: note:   'c10::attr::end'
src/learning/pytorch_test.cpp:14:1: error: expected '}' at end of input
 }

Expected behavior

I believe this should pretty print the submodules…

Environment

• GCC version: (Ubuntu 7.4.0-1ubuntu1~18.04.1) 7.4.0
• PyTorch Version (e.g., 1.0): 1.4
• OS (e.g., Linux): Ubuntu 18.04.1 LTS
• How you installed PyTorch (conda, pip, source): Linux CPU-only binary
• Build command you used (if compiling from source): n/a
• Python version: n/a
• CUDA/cuDNN version: n/a
• GPU models and configuration: n/a
• Any other relevant information: Using GCC 7 via Bazel (see trace above for full compile flags)

Additional context

Also, is there way to initialize an empty ModuleList an do operations on it? If I try to push_back on an empty ModuleList I get what(): Accessing empty ModuleHolder (get at external/pytorch/libtorch/include/torch/csrc/api/include/torch/nn/pimpl.h:107) which makes it not so useful for my use-case of creating variable sized networks at runtime.

cc @yf225

Im learning c++ 11 and i found this error

error when compiled with GCC

g++ test.cpp -o test -lsfml-graphics -lsfml-window -lsfml-system -std=c++11
test.cpp: In function ‘int main()’:
test.cpp:6:14: error: ‘begin’ was not declared in this scope
  for(auto& b:a)
              ^
test.cpp:6:14: note: suggested alternative:
In file included from /usr/include/c++/4.9/bits/basic_string.h:42:0,
                 from /usr/include/c++/4.9/string:52,
                 from /usr/include/c++/4.9/bits/locale_classes.h:40,
                 from /usr/include/c++/4.9/bits/ios_base.h:41,
                 from /usr/include/c++/4.9/ios:42,
                 from /usr/include/c++/4.9/ostream:38,
                 from /usr/include/SFML/System/Err.hpp:32,
                 from /usr/include/SFML/System.hpp:34,
                 from /usr/include/SFML/Window.hpp:32,
                 from /usr/include/SFML/Graphics.hpp:32,
                 from test.cpp:1:
/usr/include/c++/4.9/initializer_list:89:5: note:   ‘std::begin’
     begin(initializer_list<_Tp> __ils) noexcept
     ^
test.cpp:6:14: error: ‘end’ was not declared in this scope
  for(auto& b:a)
              ^
test.cpp:6:14: note: suggested alternative:
In file included from /usr/include/c++/4.9/bits/basic_string.h:42:0,
                 from /usr/include/c++/4.9/string:52,
                 from /usr/include/c++/4.9/bits/locale_classes.h:40,
                 from /usr/include/c++/4.9/bits/ios_base.h:41,
                 from /usr/include/c++/4.9/ios:42,
                 from /usr/include/c++/4.9/ostream:38,
                 from /usr/include/SFML/System/Err.hpp:32,
                 from /usr/include/SFML/System.hpp:34,
                 from /usr/include/SFML/Window.hpp:32,
                 from /usr/include/SFML/Graphics.hpp:32,
                 from test.cpp:1:
/usr/include/c++/4.9/initializer_list:99:5: note:   ‘std::end’
     end(initializer_list<_Tp> __ils) noexcept
     ^

error when compiled with clang

clang++ test.cpp -o test -lsfml-graphics -lsfml-window -lsfml-system -std=c++11
test.cpp:6:13: error: invalid range expression of type 'sf::VertexArray'; no
      viable 'begin' function available
        for(auto& b:a)
                   ^~
1 error generated.