https://stackoverflow.com/questions/10422034/when-to-use-extern-in-c This comes in useful when you have global variables. You declare theexistenceof global variables in a header, so that each source file that includes the header knows about it, but you only need to “define” it once in ...
准确说起来,变量与函数是相同的,都分为声明和定义,即在前面加上extern,只不过出于简单的目的,函数的声明省略了extern关键字,函数不能再声明(除非是定义)处定义函数体。我们通常的变量声明主要是声明变量的类型(编译器认为是分配内存的方式):int variable;这已经有足够的信息令编译器(在声明的地方)分配内存。希望可以...
This helps to avoid naming conflicts when the same variable or function name is used in multiple source files.”(extern关键字允许我们在一个源文件中声明一个在另一个源文件中定义的变量或函数。这有助于避免在多个源文件中使用相同的变量或函数名时产生命名冲突。) 3.2 实现跨文件访问 (Enabling Cross-...
在英语口语中,我们可以这样描述extern关键字的这个用途:“The extern keyword allows us to declare a variable or function in one source file that is defined in another. This helps to avoid naming conflicts when the same variable or function name is used in multiple source files.”(extern关键字允许...
extern"C"{charShowChar(charch);charGetChar(void); }// Define the two functions// ShowChar and GetChar with C linkage.extern"C"charShowChar(charch){putchar(ch);returnch; }extern"C"charGetChar(void){charch; ch = getchar();returnch; }// Declare a global variable, errno, with C ...
Every compiler is required to provide "C" linkage A linkage specification shall occur only in namespace scope All function types, function names and variable names have a language linkage See Richard's Comment: Only function names and variable names with external linkage have a language linkage Tw...
Verwendung von extern "C" in C++ Wir verwenden das Schlüsselwort extern, um globale Variablen zu definieren, die auch als externe Variablen bekannt sind und außerhalb der Methode (Funktion) definiert werden. Wir können diese Variablen in einem Programm verwenden und den Wert mithilfe vo...
extern "C" is a linkage-specification Every compiler is required to provide "C" linkage a linkage specification shall occur only in namespace scope all function types, function names and variable names have a language linkage See Richard's Comment: Only function names and variable names with ex...
extern_c 的用法 热度: Audi A6 Der extern geregelte Klimakompressor 热度: extern用法详解(Externusagedetail) Externusagedetail 1,thebasicexplanationexterncanbeplacedbeforeavariable orfunction,inordertodefinevariablesorfunctionsdefined inotherfiles,whichpromptsthecompilertofindits ...
In aconstvariable declaration, it specifies that the variable has external linkage. Theexternmust be applied to all declarations in all files. (Globalconstvariables have internal linkage by default.) extern "C"specifies that the function is defined elsewhere and uses the C-language calling conventio...