我正在尝试使用R统计软件中的Rcpp包。不幸的是，我不能用 sourceCpp 函数编译一个基本的例子。我的玩具示例如下：

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
int hello(int a)
{
    return a;
}

保存到文件“helloworldR.cpp。
然后当我调用 sourceCpp 时：

library(Rcpp)
sourceCpp("helloworldR.cpp")

我得到以下错误：

In file included from /home/userD/R/x86_64-pc-linux-gnu-library/3.4/Rcpp/include/RcppCommon.h:65:0,
                  from /home/master/R/x86_64-pc-linux-gnu-library/3.4/Rcpp/include/Rcpp.h:27,
                  from helloworldR.cpp:1:
 /home/userD/map:1:1: error: stray ‘\177’ in program
  ^?ELF^B^A^A         ^B > ^A    ^K@     @       Xw          @ 8   @   ^] ^F   ^E
  ^
 /home/userD/map:1:8: warning: null character(s) ignored

make: *** [helloworldR.o] Error 1
g++  -I/usr/local/lib/R/include -DNDEBUG   -I"/home/master/R/x86_64-pc-linux-gnu-library/3.4/Rcpp/include" -I"/home/userD" -I/usr/local/include   -fpic  -g -O2  -c helloworldR.cpp -o helloworldR.o
 /usr/local/lib/R/etc/Makeconf:168: recipe for target 'helloworldR.o' failed
 Error in sourceCpp("helloworldR.cpp") :
   Error 1 occurred building shared library.

但是如果我把代码作为字符串，它就可以工作了：

sourceCpp(code = "#include <Rcpp.h>
 + using namespace Rcpp;
 +
 + // [[Rcpp::export]]
 + int hello(int a)
 + {
 +   return a;
 + }
 + ")
 > hello(2)
 [1] 2

你觉得会是什么？以下是我的会话信息：

sessionInfo()
 R version 3.4.3 (2017-11-30)
 Platform: x86_64-pc-linux-gnu (64-bit)
 Running under: Ubuntu 16.04.3 LTS

 Matrix products: default
 BLAS: /usr/local/lib/R/lib/libRblas.so
 LAPACK: /usr/local/lib/R/lib/libRlapack.so

 locale:
  [1] LC_CTYPE=ca_ES.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=ca_ES.UTF-8        LC_COLLATE=ca_ES.UTF-8
  [5] LC_MONETARY=ca_ES.UTF-8    LC_MESSAGES=ca_ES.UTF-8
  [7] LC_PAPER=ca_ES.UTF-8       LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
 [11] LC_MEASUREMENT=ca_ES.UTF-8 LC_IDENTIFICATION=C

 attached base packages:
 [1] stats     graphics  grDevices utils     datasets  methods   base

 other attached packages:
 [1] ggplot2_2.2.1 Rcpp_0.12.15

 loaded via a namespace (and not attached):
  [1] colorspace_1.3-2 scales_0.5.0     compiler_3.4.3   lazyeval_0.2.1
  [5] plyr_1.8.4       tools_3.4.3      pillar_1.1.0     gtable_0.2.0
  [9] tibble_1.4.2     grid_3.4.3       rlang_0.1.6      munsell_0.4.3