API是人类使用的。我们编写源代码。当我们编写程序并想要使用一些库函数时，我们编写如下代码:

long howManyDecibels = 123L;
int ok = livenMyHills(howManyDecibels);

and we needed to know that there is a method livenMyHills(), which takes a long integer parameter. So as a Programming Interface it's all expressed in source code. The compiler turns this into executable instructions which conform to the implementation of this language on this particular operating system. And in this case result in some low level operations on an Audio unit. So particular bits and bytes are squirted at some hardware. So at runtime there's lots of Binary level action going on which we don't usually see.

在二进制级别，必须对在二进制级别传递的字节有一个精确的定义，例如4字节整数中的字节顺序，或者复杂数据结构的布局——是否有填充字节来对齐一些值。这个定义就是ABI。

API是人类使用的。我们编写源代码。当我们编写程序并想要使用一些库函数时，我们编写如下代码:

long howManyDecibels = 123L;
int ok = livenMyHills(howManyDecibels);

and we needed to know that there is a method livenMyHills(), which takes a long integer parameter. So as a Programming Interface it's all expressed in source code. The compiler turns this into executable instructions which conform to the implementation of this language on this particular operating system. And in this case result in some low level operations on an Audio unit. So particular bits and bytes are squirted at some hardware. So at runtime there's lots of Binary level action going on which we don't usually see.

在二进制级别，必须对在二进制级别传递的字节有一个精确的定义，例如4字节整数中的字节顺序，或者复杂数据结构的布局——是否有填充字节来对齐一些值。这个定义就是ABI。

这是我的外行解释:

API——考虑包含文件。它们提供编程接口。 ABI——想想内核模块。当你在某个内核上运行它时，它必须同意如何在没有包含文件的情况下进行通信，即作为低级二进制接口。

我经常在api不兼容的更改或abi不兼容的更改的意义上遇到这些术语。

API更改本质上是使用以前版本编译的代码将不再工作。这可能是因为您向函数添加了参数，或者更改了在本地代码之外可访问的内容的名称。任何时候，当您更改一个头文件时，它就会迫使您更改.c/.cpp文件中的某些内容，您就做了一个api更改。

ABI更改是指已经根据版本1编译的代码将不再使用版本2的代码库(通常是库)。这通常比与api不兼容的更改更难跟踪，因为像向类添加虚拟方法这样简单的事情可能与ABI不兼容。

我发现了两种非常有用的资源，用于了解什么是ABI兼容性以及如何保存它:

在KDE项目中使用c++的做和不做的列表 Ulrich Drepper的《如何编写共享库》(glibc的主要作者)

ABI指的是目标文件/库和最终二进制文件的布局，从成功链接、加载和执行某些二进制文件的角度出发，而不会因为二进制文件不兼容而出现链接错误或逻辑错误。

The binary format specification (PE, COFF, ELF, .obj, .o, .a, .lib (import library, static library), .NET assembly, .pyc, COM .dll): the headers, the header format, defining where the sections are and where the import / export / exception tables are and the format of those The instruction set used to encode the bytes in the code section, as well as the specific machine instructions The actual signature of the functions and data as defined in the API (as well as how they are represented in the binary (the next 2 points)) The calling convention of the functions in the code section, which may be called by other binaries (particularly relevant to ABI compatibility being the functions that are actually exported) The way data is represented and aligned in the data section with respect to its type (particularly relevant to ABI compatibility being the data that is actually exported) The system call numbers or interrupt vectors hooked in the code The name decoration of exported functions and data Linker directives in object files Preprocessor / compiler / assembler / linker flags and directives used by the API programmer and how they are interpreted to omit, optimise, inline or change the linkage of certain symbols or code in the library or final binary (be that binary a .dll or the executable in the event of static linking)

The bytecode format of .NET C# is an ABI (general), which includes the .NET assembly .dll format. The virtual machine that interprets the bytecode has a specific ABI that is C++ based, where types need to be marshalled between native C++ types that the native code's specific ABI uses and the boxed types of the virtual machine's ABI when calling bytecode from native code and native code from bytecode. Here I am calling an ABI of a specific program a specific ABI, whereas an ABI in general, such as 'MS ABI' or 'C ABI' simply refers to the calling convention and the way structures are organised, but not a specific embodiment of the ABI by a specific binary that introduces a new level of ABI compatibility concerns.

An API refers to the set of type definitions exported by a particular library imported and used in a particular translation unit, from the perspective of the compiler of a translation unit, to successfully resolve and check type references to be able to compile a binary, and that binary will adhere to the standard of the target ABI, such that if the library that actually implements the API is also compiled to a compatible ABI, it will link and work as intended. If the API is updated the application may still compile, but there will now be a binary incompatibility and therefore a new binary needs to be used.

API包括:

函数，变量，类，对象，常量，它们的名称，类型和定义，以正确的语法和语义方式编码 这些函数实际做什么，以及如何在源语言中使用它们 需要包含的源代码文件/为了使用它们而需要链接到的二进制文件，以及它们的ABI兼容性

API:应用程序接口

这是您从应用程序/库中公开的公共类型/变量/函数集。

在C/ c++中，这是在应用程序附带的头文件中公开的内容。

ABI:应用程序二进制接口

这就是编译器构建应用程序的方式。 它定义了一些东西(但不限于):

参数如何传递给函数(寄存器/堆栈)。 谁从堆栈中清除参数(调用方/被调用方)。 返回值的位置。 异常如何传播。