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问题 I am not sure why htons and ntohs both exist in the standard library. They do exactly the same thing -- unless I'm confused somehow! The same goes for htonl and ntohl . 回答1: They make for self-documenting code that tells the reader whether the data is in host- or network- order. 回答2: This is in case a machine has some sort of unusual endianness besides big-endian or little-endian that isn't one or more simple byte swaps. For example, if the value 0x0A0B0C0D was represented internally as 0B 0C

问题 On my node server, the following code works axios.get('http://localhost:8080/myPath') // works But relative pathes don't work axios.get('/myPath') // doesn't work I get this error : message:"connect ECONNREFUSED 127.0.0.1:80" port:80 How can I get the relative url work like in the browser ? Relative path should be hitting on port 8080, not 80. Where do I set that on my node server ? 回答1: Create a new instance with custom configuation. like below var instance = axios.create({ baseURL: 'http:/

问题 I have the following problem: #include <vector> #include <tuple> using namespace std; template< size_t... N_i, typename Ts... > class A { // ... private: std::vector<size_t> _v = { N_i... }; std::tuple<Ts...> _t; }; int main() { A<1> a; } As you can see above, I try to define multiple parameter packs as template arguments of the class A . Unfortunately, the code does not compile: error: expected nested-name-specifier before 'Ts' How can I define multiple parameter packs for this example? 回答1:

问题 I have a dataframe, df: id volume saturation time_delay_normalised speed BPR_free_speed BPR_speed Volume time_normalised 27WESTBOUND 580 0.351515152 57 6.54248366 17.88 15.91366177 580 1.59375 27WESTBOUND 588 0.356363636 100 5.107142857 17.88 15.86519847 588 2.041666667 27WESTBOUND 475 0.287878788 64 6.25625 17.88 16.51161331 475 0.666666667 27EASTBOUND 401 0.243030303 59 6.458064516 17.88 16.88283672 401 1.0914583333 27EASTBOUND 438 0.265454545 46 7.049295775 17.88 16.70300418 438 1

问题 I am using FTP over implicit SSL to upload some files. I encountered the following error message [Command] PWD [Response] 257 "/" is current directory. [Command] PWD [Response] 257 "/" is current directory. [Command] TYPE A [Response] 200 Type set to A [Command] PWD [Response] 257 "/" is current directory. [Command] PASV [Response] 227 Entering Passive Mode (10,0,0,19,195,113) [Command] LIST -aL [Response] 521 PROT P required [Command] PWD [Response] 257 "/" is current directory. [Command]

问题 I am using FTP over implicit SSL to upload some files. I encountered the following error message [Command] PWD [Response] 257 "/" is current directory. [Command] PWD [Response] 257 "/" is current directory. [Command] TYPE A [Response] 200 Type set to A [Command] PWD [Response] 257 "/" is current directory. [Command] PASV [Response] 227 Entering Passive Mode (10,0,0,19,195,113) [Command] LIST -aL [Response] 521 PROT P required [Command] PWD [Response] 257 "/" is current directory. [Command]

问题 I am using FTP over implicit SSL to upload some files. I encountered the following error message [Command] PWD [Response] 257 "/" is current directory. [Command] PWD [Response] 257 "/" is current directory. [Command] TYPE A [Response] 200 Type set to A [Command] PWD [Response] 257 "/" is current directory. [Command] PASV [Response] 227 Entering Passive Mode (10,0,0,19,195,113) [Command] LIST -aL [Response] 521 PROT P required [Command] PWD [Response] 257 "/" is current directory. [Command]

问题 I am doing a forest plot and want to save it to a PDF file. My forest plot is oversize (8in*20in). It can fit in a one page PDF like this: dev.print(pdf, file="C:\\Work\\plot.pdf", width=8, height=20); But then it is too long: When I print this PDF on a A4 paper, it has to be shrinked to fit the paper. So I want to save it to a two-page PDF file (from R). Ps: it is not a question about how to set the printer. How to do this? 回答1: So, you are able to generate an 8in x 20in == 203.2mm x 508mm =

问题 I have the following problem: #include <vector> #include <tuple> using namespace std; template< size_t... N_i, typename Ts... > class A { // ... private: std::vector<size_t> _v = { N_i... }; std::tuple<Ts...> _t; }; int main() { A<1> a; } As you can see above, I try to define multiple parameter packs as template arguments of the class A . Unfortunately, the code does not compile: error: expected nested-name-specifier before 'Ts' How can I define multiple parameter packs for this example? 回答1:

问题 I have the following problem: #include <vector> #include <tuple> using namespace std; template< size_t... N_i, typename Ts... > class A { // ... private: std::vector<size_t> _v = { N_i... }; std::tuple<Ts...> _t; }; int main() { A<1> a; } As you can see above, I try to define multiple parameter packs as template arguments of the class A . Unfortunately, the code does not compile: error: expected nested-name-specifier before 'Ts' How can I define multiple parameter packs for this example? 回答1: