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-...
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-...
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 ...
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 ...
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。希望可以帮到你 参考资料:《thinking in C++》 本回答由网友推荐 举报| 答案纠错 | 评论(1) 8 1 朋御天下 采纳率:40% 来自团队:C* 擅长: 电脑装机/选购 办公软件...
Earlier I showed the C extern keyword applied to variable declarations. More generally, extern can be applied to declarations. There are two kinds of thing you can declare in C: variables and functions. So the extern keyword can also be applied to function declarations. For example:extern...
When modifying a variable, extern specifies that the variable has static duration (it is allocated when the program begins and deallocated when the program ends). The variable or function may be defined in another source file, or later in the same file. In C++, when used with a string, ...
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...
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...
In this case, theexternsignifies the the variableiis not local to this file and that its definition will occur elsewhere. Any declaration that includes an explicit initializer is a definition. We can provide an initializer on a variable defined asextern, but doing so overrides theextern. Anexter...