calling a function without a prototype
时间: 2024-06-07 16:08:30 浏览: 18
Calling a function without a prototype is not recommended because the compiler does not know the return type and arguments of the function. This can lead to unexpected behavior or errors during runtime. In C, if a function is called without a prototype, the compiler assumes that the function returns an integer and takes an unspecified number of arguments. To avoid this, it is recommended to declare the function prototype before calling it. This informs the compiler about the return type and arguments of the function.
相关问题
已经声明原型了,还出错calling a function without a prototype
这通常发生在您尝试调用一个未在程序前面声明或定义的函数时。在大多数情况下,您应该考虑在程序开头声明函数原型或包含函数定义。这样编译器就能够识别函数并检查参数类型和正确性。如果您已经声明了原型,但仍然报错,可能存在其他代码问题,请检查您的代码。
calling a private constructor
A private constructor in a class can only be called within the class itself. This means that you cannot create an instance of the class from outside the class using the new operator, because the constructor is not accessible.
However, there are some situations where you may want to call a private constructor. One common scenario is when you want to implement the Singleton design pattern, where you ensure that only one instance of a class can be created.
To call a private constructor in C++, you can use a static member function of the class. This function can access the private constructor and create an instance of the class. For example:
```cpp
class MyClass {
private:
MyClass() {} // private constructor
public:
static MyClass* getInstance() {
static MyClass instance; // calls the private constructor
return &instance;
}
};
```
In this example, the private constructor of MyClass can only be called by the static member function getInstance(). This function creates a static instance of MyClass and returns a pointer to it. Because the instance is static, it will only be created once and subsequent calls to getInstance() will return the same instance.
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