我不是一名专业的C程序员,而且我最近在C中做了一件让我遇到以下问题的技巧.
我的任务目标:复制特定的非系统线程(实际上是协作线程)安全模块,以创建系统线程安全版本,以支持系统中的不同需求.但是,我们决定创建一个命名空间来保护C头文件中的系统线程版本,而不是创建sys_XXX函数以保持兼容性.我实际上可以将它包含在CPP文件中并愉快地工作但我刚刚意识到我的funcInit调用在它到达CPP文件控件之前没有被调用.不幸的是,协作线程版本的这个init在C文件中.现在我需要从同一个地方初始化我的系统线程安全版本,但我已被编译错误阻止,这是我知道很难解决的.
编译错误日志: –
In file included from sysinit.c:87: sys_unicode.h:39: error: expected '=',',';','asm' or '__attribute__' before 'SystemThreadUtils' <== corresponds to line [namespace SystemThreadUtils {] sysinit.c:88: sysinit.c:512: error: expected identifier or '(' before string constant <== corresponds to line [extern "C" bool SystemThreadUtils::funcInit(void);] sysinit.c:513: error: expected identifier or '(' before string constant <== corresponds to line [extern "C" bool SystemThreadUtils::funcTerm(void);] sysinit.c: In function 'SysInit': sysinit.c:817: error: 'SystemThreadUtils' undeclared (first use in this function) <= corresponds to line [SystemThreadUtils::funcInit();] sysinit.c:817: error: (Each undeclared identifier is reported only once sysinit.c:817: error: for each function it appears in.) sysinit.c:817: error: expected ')' before ':' token sysinit.c: In function 'SysTerm': sysinit.c:2737: error: expected expression before ':' token <== corresponds to line [SystemThreadUtils::funcTerm();] sysinit.c:2737: warning: label 'SystemThreadUtils' defined but not used
C头文件(unicode.h):
// all functions called from the C source file funcInit(); funcA(); funcB(); funcTerm();
C头文件(unicode.c):
// all functions called from the C source file funcInit() { } funcA() { } funcB() { } funcTerm() { }
C头文件(sys_unicode.h):
#include "unicode.h" namespace SystemThreadUtils { // below functions called from the C source file extern "C" funcInit(); extern "C" funcTerm(); // below functions called from the CPP source file funcA(); funcB(); }
C源定义(sys_unicode.cpp):
#include "sys_unicode.h" namespace SystemThreadUtils { // below functions are called from C source funcInit() { } funcTerm() { } // below methods are called from CPP source funcA() { } funcB() { } }
CPP源#1(utils.cpp):
#include "sys_unicode.h" using namespace SystemThreadUtils; utils::utils_init() { funcA(); funcB(); }
C源#2(sysinit.c):
#include "sys_unicode.h" extern "C" bool SystemThreadUtils::funcInit(void); extern "C" bool SystemThreadUtils::funcTerm(void); SysInit () { funcInit(); // non system thread safe version SystemThreadUtils::funcInit(); // system thread safe version } SysTerm () { funcTerm(); // non system thread safe version SystemThreadUtils::funcTerm(); // system thread safe version }
解决方法
你不能在C中使用命名空间,在C中也不允许使用extern“C”.所以可能是一个解决方案:你的C模块在命名空间SystemThreadUtils中定义了一组需要在C-Code中调用的函数.由于您不能直接执行此操作,因此必须围绕它们编写符合C的包装器:
//C/C++ - header "sys_unicode_for_c.h" #ifdef __cplusplus extern "C" { #endif void STU_funcInit(); void STU_funcTerm(); #ifdef __cplusplus } //end extern "C" #endif
//C++-source: sys_unicode_for_c.hpp #include "sys_unicode.h" extern "C" { void STU_funcInit() { SystemThreadUtils::funcInit(); } void STU_funcTerm() { SystemThreadUtils::funcTerm(); } }