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This article will explain in detail the example analysis of the inappropriate use of C++ inline functions. The content of the article is of high quality, so the editor shares it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

The various applications in C++ language is a very advanced content, in which the grammar, features and standard class libraries are worthy of in-depth study. C++ inline function is one of the more important contents. Here we summarize the environments in which C++ inline functions are not suitable for use.

Inlining can improve the efficiency of function execution, why not define all functions as C++ inline functions? If all functions are inline functions, do you still need the keyword "inline"? Inlining is at the cost of code expansion (replication), which only saves the overhead of function calls, thus improving the efficiency of function execution. If the time it takes to execute the code in the body of the function is more expensive than the function call, then the efficiency gain will be very small. On the other hand, every call to an inline function will copy the code, which will increase the total code of the program and consume more memory space.

C++ inline functions are not suitable for the following situations:

(1) if the code in the function body is long, the use of inline will result in high memory consumption.

(2) if there is a loop in the body of the function, the time to execute the code in the body of the function is more expensive than the cost of the function call. The constructor and destructor of a class can easily be misunderstood as being more efficient using inlining. Be careful that constructors and destructors may hide behaviors, such as "secretly" executing the constructors and destructors of a base class or member object. So don't casually put the definition bodies of constructors and destructors in class declarations. A good compiler will automatically cancel unworthy inlines based on the definition body of the function (which further suggests that inline should not appear in the function declaration).

Note:

C++ inline functions can not only remove the efficiency burden caused by function calls, but also retain the advantages of general functions. However, inline functions are not drugs, and in some cases they can even degrade the performance of programs. Therefore, it should be used with caution.

1. Let's first look at the benefits of inline functions: from a user's point of view, C++ inline functions look like ordinary functions. They can have parameters and return values, or they can have their own scope. However, it does not introduce the burden of normal function calls. In addition, it can be safer and easier to debug than macros.

Of course, you should be aware that inline specifier is only a recommendation to the compiler, and the compiler has the right to ignore this recommendation. So how does the compiler decide whether a function is inlined or not? In general, key factors include the size of the function body, whether any local objects are declared, the complexity of the function, and so on.

2. What happens if a function is declared as inline but is not inlined? In theory, when the compiler refuses to inline a function, that function will be treated like a normal function, but there will be other problems. For example, the following code:

/ / filename Time.h # include # include using namespace std; class Time {public: inline void Show () {for (int I = 0; I

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