register , pascal 是传递参数 从 左 到 右.
StdCall是传递参数 从 右 到 左.
safecall 指示符用与com和异常处理.如果一个函数用safecall声明,就可以
确保任何异常都被传播给函数的调用者,并且将异常转换为HResult类型的返回
值.SafeCall也意味者采用StdCall 调用约定.
safecall的函数声明如下:
function hello(i:intger) :String; SafeCall;
编译器这样看待这个代码:
function hello(i:intger) :String; HResult;SafeCall;
然后编译器会给整个函数内容加上try ..except 并且捕获触发的
任何异常.并调用safecallexceptionhandler(),将异常转换成
HResult类型值.
另附 delphi help :
When you declare a procedure or function, you can specify a calling convention using one of the directives register, pascal,
cdecl, stdcall, and safecall. For example,function MyFunction(X, Y: Real): Real; cdecl; ...Calling conventions determine the order in which parameters are passed to the routine. They also affect the removal of parameters from the stack, the use of registers for passing parameters, and error and exception handling. The default calling convention is register.The register and pascal conventions pass parameters from left to right; that is, the leftmost parameter is evaluated and passed first and the rightmost parameter is evaluated and passed last. The cdecl, stdcall, and safecall conventions pass parameters from right to left.
For all conventions except cdecl, the procedure or function removes parameters from the stack upon returning. With the cdecl convention, the caller removes parameters from the stack when the call returns.The register convention uses up to three CPU registers to pass parameters, while the other conventions pass all parameters on the stack.
The safecall convention implements exception 揻irewalls.?On Windows, this implements interprocess COM error notification.The table below summarizes calling conventions.Directive Parameter order Clean-up Passes parameters in registers?
register Left-to-right Routine Yes
pascal Left-to-right Routine No
cdecl Right-to-left Caller No
stdcall Right-to-left Routine No
safecall Right-to-left Routine No
The default register convention is the most efficient, since it usually avoids creation of a stack frame. (Access methods for published properties must use register.) The cdecl convention is useful when you call functions from shared libraries written in C or C++, while stdcall and safecall are recommended, in general, for calls to external code. On Windows, the operating system APIs are stdcall and safecall. Other operating systems generally use cdecl. (Note that stdcall is more efficient than cdecl.)The safecall convention must be used for declaring dual-interface methods. The pascal convention is maintained for backward compatibility. For more information on calling conventions, see Program control.
The directives near, far, and export refer to calling conventions in 16-bit Windows programming. They have no effect in 32-bit applications and are maintained for backward compatibility only.
StdCall是传递参数 从 右 到 左.
safecall 指示符用与com和异常处理.如果一个函数用safecall声明,就可以
确保任何异常都被传播给函数的调用者,并且将异常转换为HResult类型的返回
值.SafeCall也意味者采用StdCall 调用约定.
safecall的函数声明如下:
function hello(i:intger) :String; SafeCall;
编译器这样看待这个代码:
function hello(i:intger) :String; HResult;SafeCall;
然后编译器会给整个函数内容加上try ..except 并且捕获触发的
任何异常.并调用safecallexceptionhandler(),将异常转换成
HResult类型值.
另附 delphi help :
When you declare a procedure or function, you can specify a calling convention using one of the directives register, pascal,
cdecl, stdcall, and safecall. For example,function MyFunction(X, Y: Real): Real; cdecl; ...Calling conventions determine the order in which parameters are passed to the routine. They also affect the removal of parameters from the stack, the use of registers for passing parameters, and error and exception handling. The default calling convention is register.The register and pascal conventions pass parameters from left to right; that is, the leftmost parameter is evaluated and passed first and the rightmost parameter is evaluated and passed last. The cdecl, stdcall, and safecall conventions pass parameters from right to left.
For all conventions except cdecl, the procedure or function removes parameters from the stack upon returning. With the cdecl convention, the caller removes parameters from the stack when the call returns.The register convention uses up to three CPU registers to pass parameters, while the other conventions pass all parameters on the stack.
The safecall convention implements exception 揻irewalls.?On Windows, this implements interprocess COM error notification.The table below summarizes calling conventions.Directive Parameter order Clean-up Passes parameters in registers?
register Left-to-right Routine Yes
pascal Left-to-right Routine No
cdecl Right-to-left Caller No
stdcall Right-to-left Routine No
safecall Right-to-left Routine No
The default register convention is the most efficient, since it usually avoids creation of a stack frame. (Access methods for published properties must use register.) The cdecl convention is useful when you call functions from shared libraries written in C or C++, while stdcall and safecall are recommended, in general, for calls to external code. On Windows, the operating system APIs are stdcall and safecall. Other operating systems generally use cdecl. (Note that stdcall is more efficient than cdecl.)The safecall convention must be used for declaring dual-interface methods. The pascal convention is maintained for backward compatibility. For more information on calling conventions, see Program control.
The directives near, far, and export refer to calling conventions in 16-bit Windows programming. They have no effect in 32-bit applications and are maintained for backward compatibility only.
解决方案 »
免费领取超大流量手机卡，每月29元包185G流量+100分钟通话, 中国电信官方发货