Tutorials and tips on programming related to Linux systems, Web and more.
In Ubuntu 18.04 LTS, the default Go lang version is 1.10. For compatibility reason, the Ubuntu LTS will usually keep the major release version numbers for packages. However, many applications, such as Hyperledger Fabric 2.0, require a newer version of Go. In this post, let’s take a look at how to install a system level…
We know compilers like gcc can do lots smart optimization to make the program run faster. Regarding functions call optimization, gcc can do tail-call elimination to save the cost of allocating a new stack frame, and tail recursion elimination to turn a recursive function to non-recursive iterative one. gcc can even transform some recursive functions…
I don’t know why Jason Lattimer’s D365DeveloperExensions no more working after VS 2017 release? It seems D365DeveloperExtensions anymore supported for newer Visual Studio version. I am pretty much sure, some of you may be still struggling with installing Dynamics 355 Developer extension for your Visual Studio 2017 community or professional edition. Not sure why this tool has been…
Bash (GNU Bourne-Again SHell) the default shell for many Linux distributions. It is very common for scripting languages in Linux. Bash is easy and straightforward for writing small tools. However, as most tools, it has its grammars that could easily cause bugs if they are not used correctly. Here I summarize a list of good…
StoneWall is an interesting problem that requires some brain cycles yet not too complex. It is good software engineer interview question. Here is a C++ solution whose complexity is O(N). #include <stack> int solution(std::vector<int> &H) { int stones = 0; std::stack<int> heights; for (auto h: H) { while (!heights.empty() && h < heights.top()) { heights.pop();…
Static linking is preferred for some cases although it has its own various problems. Static building/linking is not always possible for some languages on some platform. For OCaml, the answer to this question is yes. In this post, we will introduce 2 methods to statically linking OCaml: static linking with runtime glibc required and static…
Java is the most regularly used programming language for the creation of web applications. This high-level programming language develops by the Sun Micro-system. This language was designed for use in the world of internet and known for fastest, secure, and most reliable language of the computing platform. One interesting fact is that Java programmers are…
How to test a path (a file or directory exists) in golang? In Bash, the [ -e ] tests can test whether a file or a directory exist. What are the corresponding Go ways for the test? You can use the `os.Stat()` and `os.IsNotExist()` standard libraries functions together to test whether a file or a…
Sparse files are common in Linux/Unix and are also supported by Windows (e.g. NTFS) and macOSes (e.g. HFS+). Sparse files uses storage efficiently when the files have a lot of holes (contiguous ranges of bytes having the value of zero) by storing only metadata for the holes instead of using real disk blocks. They are…
In many text processing tasks, we often need to check if a given string starts with a specific substring. In this article, we will demonstrate how to achieve this using the std::string::compare() function from the C++ Standard Library. The compare() function has several overloads, but the one of interest for our purpose is: int compare(size_type…
readlink -m can get canonical file name by resolving every symlinks in every component of the given path recursively. In Python, the os.readlink() function does not do so. Any equivalent function in Python to the readlink -m command line? Specifically, it does: canonicalize by following every symlink in every component of the given name recursively,…
How to iterate all dirs and files in a dir in C++? To open a dir, we can use opendir() to open a directory stream. DIR *opendir(const char *name); Then we can use readdir() to iterate the directory stream. struct dirent *readdir(DIR *dirp); Here is an example C++ program using these 2 library functions. #include…
How to remove newline characters from a string in C++? For example, a string like line 1 line 3 line 4 should be converted to line 1line 3line 4 Method 1: use `erase()` and `remove()` In short, use this code snippet: input.erase(std::remove(input.begin(), input.end(), ‘\n’), input.end()); std::remove() shifts all elements that are equal to the value…
How to get a path’s mtime in C++ on Linux? The path can be a file or a dir. You may call the standard library function lstat() for the file or dir under the path. int lstat(const char *pathname, struct stat *statbuf); From the returned stat struct, there is a field st_mtim which is the…
How to get the running process’ pid in C / C++? In C and C++, you can call the getpid() library function which is a function from the POSIX library. #include <sys/types.h> #include <unistd.h> pid_t getpid(void); getppid() returns the process ID of the calling process. An example C program to get self process ID getpid.c:…
How to get the running process’ pid in Python? In Python, you can get the pid of the current process by import os os.getpid() From the official doc: os.getpid() Return the current process id. One example os using os.getpid() to get process own ID: $ python3 Python 3.8.10 (default, Jun 22 2022, 20:18:18) [GCC 9.4.0]…
In Go lang, how to get the epoch timestamp, the number of seconds passed since the epoch? In Go, you can use the time.Now() func to get current time and its Unix() func to convert it into an epoch timestamp: import(“time”) func getEpochTime() int64 { return time.Now().Unix() } If you would convert a time string…
In Python, how to get the epoch time (the number of seconds since epoch)? In Python, you can get the epoch time by calling time.time() which return a floating number: import time print time.time() If you would like to get only the number of seconds, you may convert it to an integer. One example is…
This blog will explain about how to add a custom content in a Receipt which will be generated from MPOS in Microsoft Dynamics. Microsoft provides us with certain fields which can be put into the receipt. There are certain fields which a client will ask to show in the receipt. If the desired field is…
Introduction In this tutorial, we will be learning as how to deploy .NET Core 2.0 MVC web application on Microsoft Public Cloud i.e. Microsoft Azure, using Microsoft Visual Studio 2017 v15.3 For novice Cloud developers, aspiring .NET / Cloud architects, and all other IT professionals associated with the .NET Core framework & Cloud computing, especially…