Inline

The official version of Inline is used to define inline functions of a class. The latest version of Inline can replace macro definitions in the form of expressions in C, helping users solve the problem of frequently called functions consuming a large amount of stack space (stack memory). The keyword inline not only eliminates the shortcomings of macro definition, but also inherits the advantages of macro definition. Therefore, it is very efficient.

Inline software introduction

In C++, users can create short functions that are not actually called, and their code is expanded on the program line of each call. This process is similar to using function-like macros. In order to make a function code expand within the program line without To be called, just add the inline keyword in front of the function.

Inline is a request to the compiler, not a command

It is possible to define short functions within a class declaration. If a function is defined within a class declaration, it will automatically be converted to an inline function. There is no need to add inline before the function declaration. Keywords, constructors and destructors can also be inline functions.

Inline software features

(1) The role of inline functions

●For inline functions, C++ may directly use the function body code to replace the call to the function. This process is called inline expansion of the function body.

For small functions with only a few statements, the code for preparation and finishing work related to function calling and return is often much larger than the code of the function body itself. Therefore, for such simple, frequently used small functions, describing them as inline functions can improve operating efficiency. [3]

(2) Use inline functions with caution

Inlining is at the expense of code expansion and copying, and only saves the overhead of function calls, thus improving the execution efficiency of the function. If the time to execute the code in the function body is larger than the overhead of function calls, then the efficiency gain will be very small. On the other hand, every call to an inline function requires duplication of code, This will increase the total code size of the program and consume more memory space. Inlining should not be used in the following situations:

​ ​ 1) If the code in the function body is relatively long, using inlining will result in higher memory consumption costs.

​ ​ 2) If a loop occurs in the function body, the time to execute the code in the function body is greater than the cost of the function call.

Inline software advantages

The reason for introducing the inline keyword

In C/C++, in order to solve the problem that some frequently called small functions consume a lot of stack space (stack memory), the inline modifier is specially introduced, which is represented as an inline function.

​​ Stack space refers to the memory space where the local data of the program (that is, the data within the function) is placed.

Under the system, the stack space is limited. If it is used frequently and in large quantities, it will cause program errors due to insufficient stack space. For example, the final result of infinite loop recursive calls of functions is the exhaustion of stack memory space.

Inline update log

​ 1. Optimized some functions

​ 2. Solved many unbearable bugs