[散分][关于GetLastError的问题]

[柯本]

今天在编译fport的源码时(原在VC下的)老是报内存错,经检查原来是由于BCB返回不正确的GetLastError所致,郁闷之余,作了一个测试,新建项目,加一按钮
void __fastcall TForm1::Button1Click(TObject *Sender)
{
ShowMessage(SysErrorMessage(GetLastError()));
}
居然显示:窗口没有滚动条.
不知大家有无类似问题,来者有分

[老之]

：）

[土著巫师]

1、The GetLastError function retrieves the calling thread's last-error code value. The last-error code is maintained on a per-thread basis. Multiple threads do not overwrite each other's last-error code.

2、Most functions that set the thread's last error code value set it when they fail; a few functions set it when they succeed. Function failure is typically indicated by a return value error code such as zero, NULL, or –1. Some functions call SetLastError under conditions of success; those cases are noted in each function's reference page.

3、You should call the GetLastError function immediately when a function's return value indicates that such a call will return useful data. That is because some functions call SetLastError with a zero when they succeed, wiping out the error code set by the most recently failed function.

[wmlalison]

接分 ^_^

[cczlp]

应该在一个API之后紧接着调用GetLastError， BCB的函数已经执行了N个API，
GetLastError返回的已经不是你要的了。

[rudolf_he]

学习

[ccrun.com]

同意cczlp

[tianshu888]

接分了

[BlueDeepOcean]

学习，同时关注，并且继续往上顶！

[daydayup234]

only 接分

[netsys2]

8错

[wangxintu]

我的显示“操作成功完成”

[柯本]

我也明白cczlp(不惑)所说,问题是我是在函数后直接用的,如下:
...
hMemory = MapViewOfFile(hSection, FILE_MAP_READ,
0, 0x30000, 0x1000);
if (GetLastError() != 0) return NULL;
...
GetLastError()返回为127(找不到指定程序),而同样的代码在VC下没问题
我只能改成
if (hMemory==NULL) return NULL;
没问题

[scjpsz1860]

快乐接分！：）

[kwokwinglau]

路过接分。

[jone7319]

没见过

[柯本]

继续...

[ccrun.com]

很多API本身的返回值就可以表示函数执行成功与否，单纯的靠GetLastError有失误的。

[pp616]

先SetLastError(0);
再调功能代码。
然后GetLastError();

[caizhen2000_82]

jf

[柯本]

感谢各位参与,祝大家五.一快乐!