直接cast肯定是不對(duì)的，
正確的寫法是：

using func=int(*)(int);
using FuncType = std::function<int(int)>;
FuncType f{reinterpret_cast<func>(dlsym(libHandle, "func"))};

create-react-app創(chuàng)建的默認(rèn)demo應(yīng)該是有內(nèi)容的，你是不是自己修改了寫啥？在App.js或者index.js里邊。
這跟你加不加homepage關(guān)系不大哈

困擾了快一周了，問題終于解決，算法本身沒問題，只是第三方的系統(tǒng)會(huì)縮放目標(biāo)圖片，計(jì)算時(shí)加上這個(gè)縮放比例定位即準(zhǔn)確。

檢查open函數(shù)的返回值，看看是否打開成功

在我機(jī)器上用g++ 6.4.0，不開啟優(yōu)化，a、b的地址還是由高到低，開啟優(yōu)化后就變成由低到高了：

~ $ g++ test.cpp
~ $ ./a
0xffffcbbc
0xffffcbb8
0x600000480
0x6000004a0
~ $ g++ test.cpp -O2
~ $ ./a
0xffffcba8
0xffffcbac
0x600000480
0x6000004a0

這里是不是有什么玄機(jī)？然而用clang++再試，發(fā)現(xiàn)不管開不開啟優(yōu)化，都是由高到低分配的。編譯器可以自行安排變量的地址，只要保證程序執(zhí)行結(jié)果正確即可。所謂“棧向低地址生長”只是一個(gè)實(shí)現(xiàn)的模型，并不是絕對(duì)的。

至于c、d，更沒有規(guī)定說要連續(xù)分配了。實(shí)際上在向操作系統(tǒng)申請(qǐng)內(nèi)存的時(shí)候，一般都是多給一些的，用不滿就浪費(fèi)了，沒什么大不了。

你的 rabbitmq 服務(wù)是不是沒有保持在后臺(tái)運(yùn)行，我記得 rabbitmq-server start 然后 ctrl+c 是會(huì)退出服務(wù)的，你用 rabbitmq-server –detached 讓它在后臺(tái)運(yùn)行再試試 rabbitmqctl status

你的token在哪里？？

• 如果是放在cookie中，就不用管了，ajax自己會(huì)帶上的。
• 如果不是，header上手動(dòng)放入token，一下舉例

$.ajax({
????type:"POST",
????url:url,
????data:formData,
????//在請(qǐng)求前設(shè)置請(qǐng)求頭 在請(qǐng)求頭里面設(shè)置設(shè)置請(qǐng)求頭的信息
????beforeSend: function(request) {
????????????request.setRequestHeader("Authorization", token1);
????},
????success:function(res){
????    console.log(res);
????}
});

1. 關(guān)于 pyo 優(yōu)化:

參考鏈接

• When the Python interpreter is invoked with the -O flag, optimized code is generated and stored in .pyo files. The optimizer currently doesn't help much; it only removes assert statements. When -O is used, all bytecode is optimized; .pyc files are ignored and .py files are compiled to optimized bytecode.
• Passing two -O flags to the Python interpreter (-OO) will cause the bytecode compiler to perform optimizations that could in some rare cases result in malfunctioning programs. Currently only __doc__ strings are removed from the bytecode, resulting in more compact .pyo files. Since some programs may rely on having these available, you should only use this option if you know what you're doing.
• Your program doesn't run any faster when it is read from a .pyc or .pyo file than when it is read from a .py file; the only thing that's faster about .pyc or .pyo files is the speed with which they are loaded.
• When a script is run by giving its name on the command line, the bytecode for the script is never written to a .pyc or .pyo file. Thus, the startup time of a script may be reduced by moving most of its code to a module and having a small bootstrap script that imports that module. It is also possible to name a .pyc or .pyo file directly on the command line.

2. 關(guān)于 pyd:

pyd 可以理解為 Windows DLL 文件。

參考鏈接

• Yes, .pyd files are dll’s, but there are a few differences. If you have a DLL named foo.pyd, then it must have a function PyInit_foo(). You can then write Python "import foo", and Python will search for foo.pyd (as well as foo.py, foo.pyc) and if it finds it, will attempt to call PyInit_foo() to initialize it. You do not link your .exe with foo.lib, as that would cause Windows to require the DLL to be present.
• Note that the search path for foo.pyd is PYTHONPATH, not the same as the path that Windows uses to search for foo.dll. Also, foo.pyd need not be present to run your program, whereas if you linked your program with a dll, the dll is required. Of course, foo.pyd is required if you want to say import foo. In a DLL, linkage is declared in the source code with __declspec(dllexport). In a .pyd, linkage is defined in a list of available functions.

for(int i = 0; i < n; i++) {
  if(a[i] == x) {
    cout << i << endl;
    break;              // 這里break了，下面的flag=true不會(huì)被執(zhí)行到
    flag = true;
  }
}

class SparseMat {
public:
    SparseMat(int MAXROW, int MAXCOL, int NonZeroterms);
    SparseMat MAT_transpose(SparseMat b);
private:
    int Rows, Cols, NonZeroterms;
    Trituple* SMArray;
};

SparseMat::SparseMat(int MAXROW, int MAXCOL, int NonZeroterms)
    :Rows(MAXROW), Cols(MAXCOL), NonZeroterms(NonZeroterms)
{
     SMArray = new Trituple[NonZeroterms];
}

你這個(gè)無非就是枚舉法，至于所謂加法運(yùn)算，不明白，既然是一對(duì)多，兩個(gè) for 循環(huán)？

conf 下面確實(shí)沒有cert這個(gè)路徑啊，從你的圖上看來的話

1. 你nm命令看到的那些符號(hào)的“U”表示未定義的，你可以看到它們前面沒有內(nèi)存地址信息，這些符號(hào)是定義在你引入的mxml庫中的。

2. 你是在生成可執(zhí)行程序main的失敗報(bào)錯(cuò)的吧，如果是在編譯的時(shí)候再加上-lmxml選項(xiàng)，并使用-L選項(xiàng)指定mxml庫所在的目錄。

3. 運(yùn)行時(shí)可能會(huì)遇到提示找不到libmxml.so**庫的錯(cuò)誤提示，可以把libmxml.so**庫發(fā)布到/usr/lib64目錄下，或者把libmxml.so**所在目錄配置到/etc/ld.so.conf中，然后執(zhí)行l(wèi)dconfig即可。

rxjs github上有一句話做了說明，引入Observable或Subject或Subscription最好的方式就是

To import only what you need by patching (this is useful for size-sensitive bundling):

import { Observable } from 'rxjs/Observable';

也就是說，需要什么，就去對(duì)應(yīng)的準(zhǔn)備包下引用。
尤其是當(dāng)你的應(yīng)用很大時(shí)，希望盡量壓縮打包的bundle的大小，這個(gè)時(shí)候import的路徑就尤為重要了。
如果使用這種方式 import { Observable } from 'rxjs'， 打包的時(shí)候會(huì)把rxjs下的內(nèi)容都打到bundle里面，這顯然是沒有必要的。

運(yùn)行前，需要配置bitcoin.conf，將其放在/.bitcoin/下面

QWidget::find() 僅適用于 Qt 當(dāng)前進(jìn)程創(chuàng)建的窗口，而 FindWindow() 查詢的是整個(gè)操作系統(tǒng)下的頂級(jí)窗口。
因此，你若傳遞非 Qt 當(dāng)前進(jìn)程創(chuàng)建的窗口 ID 給 QWidget::find()，它將返回 NULL。

要給其他進(jìn)程的窗口發(fā)送消息，大致流程是這樣的

1. 用 FindWindow 找到目標(biāo)窗口的頂級(jí)窗口
2. 在頂級(jí)窗口下，用 FindWindowEx 找到目標(biāo)窗口
3. 構(gòu)造需要發(fā)送的消息
4. 用 SendMessage 或 PostMessage 向目標(biāo)窗口發(fā)送消息

這一行錯(cuò)誤了，ios::ate定位到了文件末尾
ifstream outf("1.txt", ios::ate | ios::binary);

ubuntu上開GDB-Server vscode配置GDB調(diào)試連接GDB-Server調(diào)試

It must be a typographical error. There is no doubt that

$$\mathrm{dot}((p - C),(p - C)) = (x - cx) \cdot (x-c) + (y - cy) \cdot (y - cy) + (z - cz) \cdot (z - cz)$$

$\text{BTW}, \ \ \ \cdot \ \ \ \text{is much more popular than} \ \ \ \ \times \ \ \ \ \ \ast \ \ \ \ \ \text{in mathematics}$