GCC May “Save” You Some Recursive Functions Calls: an Analysis of a Function Call Stack Length Example

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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
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Bash Learning Materials

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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
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How to Install Wine 32-bit on CentOS 8

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Since version 7, RHEL and CentOS only have 64 bit versions. For some reasons, it’s better to run many Windows applications under 32 bit wine. Like How to Install Wine 32-bit on CentOS 7, this post introduce how to install 32-bit Wine on CentOS 8. Most of the mechanisms are similar yet there are differences.
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How to Convert Integers to Strings and Strings to Integers in PHP

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Conversion from integer to string and from string to integer are common operations in most applications such as C++. PHP has its uniqueness in language and standard library design. In this post, we will check methods to convert integers to strings and vice versa. Convert string to int in PHP You can cast a string
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A StoneWall Solution in C++

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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();
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How to Statically Link OCaml Programs

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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
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5 necessary PC hardware that a programmer needs to upgrade

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The world of technology has evolved drastically over the last few decades. Almost every aspect of our lives is dominated by technology. At the heart of technology lies computer programming. Computer programming is what dictates the success of the technology. I mean think about it, your smartphone, PC, ETC they all rely on programming. This
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New Linux Kernel 5.0: Features and Improvements

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Linux is the most used and well-known open-source operating system for computers, mobile devices, servers, and mainframes, etc. Linux has so many awesome features to serve its users like Live CD/USB. And it is fast, easy and free to use by computers around the world. The kernel is referred to as the essential component of
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What can we expect in Java update 2019?

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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
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Installing Zlib Library in Ubuntu Linux

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On Ubuntu (18.04 and 20.04), installing zlib reported unable to locate package zlib: $ sudo apt install zlib Reading package lists… Done Building dependency tree Reading state information… Done E: Unable to locate package zlib How to install zlib in Ubuntu? Install zlib in Ubuntu from Ubuntu package repo In Ubuntu, the zlib package is
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Handling Sparse Files on Linux

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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
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How to create a file if not exist and open it in read and write modes in C++?

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How to create a file if not exist and open it in read and write modes in C++? For example, I would like open a fstream on /tmp/cache to be able to read it and append to it. If the file does not exist yet, create one. A simple code like std::fstream fs(“/tmp/cache”, std::ios::in |
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How to not use concrete types in lambda function parameters in C++11?

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C++11 requires that lambda function parameters be declared with concrete types. This is sometimes annoying. auto is really nice, especially when the type is complex like std::vector<std::string>::iterator is quite long to type. I know C++14 allows auto in lambda functions. But how to not use concrete types in lambda function parameters in C++11? In C++11,
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How to check whether a string starts with another string in C++?

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How to check whether a string starts with another string in C++? For example, startwith(“big string here…”, “big”) –> True and startwith(“big string here…”, “small”) –> False and startwith(“big”, “big string here”) –> False The std::string::compare() standard library function of C++ can be used. int compare( size_type pos1, size_type count1, const basic_string& str ) const;
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