为什么不能将字符串文字连接到__FUNCTION__? [英] Why can't a string literal be concatenated to __FUNCTION__?

问题描述

不是__FUNCTION__字符串文字吗?我一直以为是-沿__FILE__的意思，但是我发现不能将字符串文字与其相邻地连接.如果它不是字符串文字，它的定义是什么?我无法让cscope解决它.

Isn't __FUNCTION__ a string literal? I'd always thought it was - along the lines of __FILE__, but I just discovered I can't adjacently concatenate a string literal to it. If it's not a string literal, what is it defined as? I can't get cscope to resolve it.

例如

#include <iostream>

int main( int argc, char* argv[] )
{
  std::cout << __FILE__ << std::endl;
  std::cout << __FILE__ "A" << std::endl;
  std::cout << __FUNCTION__ << std::endl;
  //std::cout << __FUNCTION__ "A" << std::endl; // Doesn't compile.
  return 0;
}

包含问题行时的错误:

>g++ --version
g++ (GCC) 4.8.3 20140911 (Red Hat 4.8.3-7)
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

>g++ -g main.cpp 
main.cpp: In function 'int main(int, char**)':
main.cpp:8:29: error: expected ';' before string constant
   std::cout << __FUNCTION__ "A" << std::endl; // Doesn't compile.

推荐答案

不是__FUNCTION__字符串文字吗?

否.

来自 https://gcc.gnu.org /onlinedocs/gcc-7.2.0/gcc/Function-Names.html

这些标识符是变量，而不是预处理器宏，并且不能用于初始化char数组或与字符串文字串联.

These identifiers are variables, not preprocessor macros, and may not be used to initialize char arrays or be concatenated with string literals.

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