C is a general-purpose computer programming language used for operating systems, games and other high performance work.

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How can we make a certain thing inbuilt in c language with our own header file?

I want to make the basic trigonometric functions in maths inbuilt functions using my own header file . so as the users can do trigonometry in c language compilers.
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3answers
348 views

Understanding how variable assignment works

When I started learning C programming a few years ago, my tutor taught me similar to most of the tutors around the world. She said me the very basic things like any int datatype is of 2 bytes memory. ...
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Why would a C executable be smaller when compared to C++ executable

I'm trying to understand why the output file sizes are significantly different when using a C and a C++ compiler. I was writing a small hello world program in C and C++, I noticed that in C version, ...
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4answers
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C/C++: Who uses the logical operator macros from iso646.h and why? [closed]

There has been some debate at work about using the merits of using the alternative spellings for C/C++ logical operators in iso646.h: and && and_eq &= bitand & bitor ...
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4answers
773 views

How bad is it calling println() often than concatenating strings together and calling it once?

I know output to the console is a costly operation. In the interest of code readability sometimes it is nice to call a function to output text twice, rather than having a long string of text as an ...
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2answers
92 views

How to handle enums in an indirection with functionpointers at ANSI-C?

Moinsen, I am somehow stucked in a design problem. Language is ANSI-C. Lets assume we have a tinkerbox of software-modules: one module for the logic Logic (at least) one module doing some logging ...
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4answers
317 views

Benefits of porting C library to C++ [closed]

Say we take any C library such as libpng or libvorbis and convert it so that it compiles as C++ (only the minimum changes to make it compile as C++ code). Can the compiler do extra optimizations when ...
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4answers
1k views

Going through The C Programming Language K&R in Visual Studio

From what I have read, K&R seems to be a good place to start learning programming in general, and C programming specifically. However, I've just started the first chapter and I have a few ...
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1answer
246 views

Suggested method for extracting a standalone C library from an existing R package?

My group has been developing an R package to simulate plant growth (see GitHub repository). The R package uses .Call to interface with C. We have decided that it would be worthwhile to create a ...
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3answers
1k views

usage of double pointers and n pointers?

I am familiar with basic C pointers. Just wanted to ask what is the actual use of double pointers or for that matter n pointer? #include<stdio.h> int main() { int n = 10 , *ptr , **ptr_ptr ; ...
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3answers
292 views

Transitioning from Java & C to C++

I learned Java and I'm pretty competent programming in it. I also learned C recently. I looked at a comparison between Java and C++ and I like C++'s features like operator overloading and its speed. ...
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2answers
155 views

Understanding Arithmetic In C

I have an embarrassingly simple question, but I need to make sure I understand this correctly. I have a *.c file with the following line: CSRConstant = ...
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2answers
1k views

Why can't arrays be passed as function arguments in C?

Following this comment, I've tried to google why, but my google-fu failed. Comment from link: [...] But the important thing is that arrays and pointers are different things in C. Assuming ...
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3answers
171 views

Use of malloc in C

Is it necessary to call free function every time we use malloc in C. I am asking this because I have seen many times that it is not called . Thank you
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10answers
7k views

Why do C arrays not keep track of their length?

What was the reasoning behind not explicitly storing an array's length with an array in C? The way I see it, there are overwhelming reasons to do so but not very many in support of the standard ...
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1answer
143 views

How to check the space complexity of this program?

I have written my version of strstr function in c. I am using a temporary array of size 26. Then is the space complexity O(1) or O(n)? This is my code : void strcheck(char t[], int n, char p[], int ...
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2answers
291 views

Why is it called a memory leak?

I am a hobbyist programmer, bit of a stickler for terminology, currently learning C and recently came across the concept of Memory Leak. Now, I do understand what it means. Dynamic memory allocated to ...
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1answer
148 views

Memory read/write access efficiency

I've heard conflicting information from different sources, and I'm not really sure which one to believe. As such, I'll post what I understand and ask for corrections. Let's say I want to use a 2D ...
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2answers
1k views

Questions about linking libraries in C

I am learning C (still very much a beginner) on Linux using the GCC compiler. I have noticed that some libraries, such as the library used with the math.h header, need to be linked in manually when ...
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1answer
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Global variable in a Linux shared library

Suppose we have the following setup under Linux, .so library named "libcnt.so" and 3 user space apps: "app1", "app2", "app3". This library does 1 simple thing, it says to the app (app dynamically ...
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3answers
181 views

Organization of DLL linked functions

This is a code organization question. I got my basic code working but when I expand it, it will be terrible. I have a DLL which I don't have a .lib for. Therefore I have to use the whole ...
4
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1answer
336 views

Why is the function called lseek(), not seek()?

The C function for seeking in a file is called lseek(). Why ins't it called just seek()?
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1answer
245 views

Are there theoretical reasons why arrays in C take less RAM than Java?

My experience is that Java requires about twice as much RAM compared to C (comparing char arrays or other comparisons). I also read in a hardware book that Java takes about twice RAM than C. Is is ...
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3answers
281 views

Why are there two different kinds of linking, i.e. static and dynamic?

I've been bitten for the n-th time now by a library mismatch between a build and deployment environment. The build environment had libruby.so.2.0 and the deployment environment had libruby.a. One ruby ...
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8answers
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Why does Clang/LLVM warn me about using default in a switch statement where all enumerated cases are covered?

Consider the following enum and switch statement: typedef enum { MaskValueUno, MaskValueDos } testingMask; void myFunction(testingMask theMask) { switch theMask { case ...
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1answer
658 views

Why are most GNU's software written in C [closed]

I am a Java developer, and I rarely write GUI program in C. However, I noticed that many GNU's projects, such as PSPP, R, Dia, etc., are written in C, instead of Java or C++. I personally don't mind ...
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3answers
169 views

How can I handle this string concatenation in C in a reusable way

I've been writing a small C application that operates on files, and I've found that I have been copy+pasting this code around my functions: char fullpath[PATH_MAX]; fullpath[0] = '\0'; ...
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4answers
732 views

Data structure for file search

I've asked this question before and I got a few answers/idea, but I'm not sure how to implement them. I'm building a telecom messaging solution. Currently, I'm using a database to save my ...
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2answers
345 views

“bug” in C++11 text by Stroustrup?

I found an apparent contradiction in the c++ text having to do with the result of the c_str() function operating on std:strings (in my copy, the definition and contradiction are on p1040). First it ...
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6answers
4k views

sizeof style: sizeof(type) or sizeof variable?

I've seen two styles of using sizeof for memory-related operations (such as in memset or malloc): sizeof(type), and sizeof variable or sizeof(variable) Which one would you prefer, or would you use ...
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1answer
139 views

Should I implement a function or a method?

Once in a while I encounter a C function in my colleagues' code. Mostly it is in some helpful objective categories, and those functions are mostly an internal calculation of something or a ...
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6answers
1k views

Should my team use some common well-regarded coding standard as a basis for its own?

The R&D team I'm in has decided to adopt a coding standard. We have only recently formed, and have too little code and common coding time of our own to base our standards/conventions document on ...
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3answers
1k views

How are negative signed values stored? [duplicate]

I was watching this video on the maximum and minimum values of signed integers. Take an example of a positive signed value - 0000 0001 The first bit denotes that the number is positive and the last ...
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1answer
652 views

How to effectively cooperate in a team having mixed background/mindset regarding OOP? [duplicate]

I've been recently assigned for a new high-performance C++ project (finance) together with 3 other guys who, like, me, refer to themselves as "primarily C/C++ programmers", meaning, all of us have ...
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6answers
652 views

Where, in an object oriented system should you, if at all, choose (C-style) structs over classes?

C and most likely many other languages provide a struct keyword for creating structures (or something in a similar fashion). These are (at least in C), from a simplified point of view like classes, ...
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3answers
119 views

Is allocating objects from a memory-pool a security anti-pattern?

In the wake of the heartbleed bug, OpenSSL has been rightly critizised for using its own freelist. With plain-old malloc, the bug would have almost certainly been found long ago. However, some kind ...
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5answers
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What's so bad about pointers in C++?

To continue the discussion in Why are pointers not recommended when coding with C++ Suppose you have a class that encapsulates objects which need some initialisation to be valid - like a network ...
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3answers
346 views

Choice between 1-dimensional and 2-dimensional array

I'm implementing the Chessboard class to represent the chessboard. I've to implement the transformations (reflections and rotations) on the chess board possible. The possible transformations includes ...
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7answers
4k views

Writing in C for Performance? [closed]

I know I have quite frequently heard that C typically has a performance advantage over C++. I didn't really think anything else of it until I realized that MSVC doesn't even seem to support the newest ...
31
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4answers
6k views

C is written in C, how is this possible? [duplicate]

Possible Duplicate: How could the first C++ compiler be written in C++? I know my question goes to the underground galaxy cave where languages are born and involves some lambda math and ...
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4answers
4k views

Why were short, int, and long invented in C?

I'm having trouble understanding, what were the exact purposes of creating the short, int, and long data types in C? The reason I ask is, it doesn't seem like their sizes are bounded -- they could be ...
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3answers
1k views

comparison of floating point numbers vs. comparsion of Integers in C [closed]

Does comparison of floating point numbers takes (considerably) longer time than comparison of Integers in C? I just wrote a C program of heap sort to sort floating point numbers. I am on ubuntu ...
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10answers
7k views

What is so difficult about pointers/recursion? [closed]

In the perils of java schools Joel discusses his experience at Penn and the difficulty of "segmentation faults". He says [segfaults are difficult until you] "take a deep breath and really try ...
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0answers
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how to find average bits per symbol using huffman code? [duplicate]

I'm trying to write a program in c for Huffman coding, but i stack.In input i have: Sample input: 4 //here i scan how many letters i have A 00 // and for everyone i scan how they are coded in ...
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0answers
326 views

using flat file vs sqlite db for frequent data grabbing in a cron job

I have some automated task to be done using certain types of logs generated on the server end of each day. Log files contains specific machine identification "MAC" that is to be re-written in to ...
3
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2answers
232 views

Advice for simple communication protocol (iPod and Arduino)

I connected iPod with Arduino using serial (UART) connection. Arduino sends 0-1023 number (so it's two bytes) as it's samples light sensor value. I'm asking about advice about simple and reliable ...
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1answer
143 views

How to implement an algorithm out-of-core?

I want to implement a parallel clustering algorithm "out-of-core" in CUDA. My CPU has 12GB of RAM and GPU has 4GB of it. What I want is that the entire dataset should be on the disk, and I can pick ...
5
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1answer
164 views

At ping, why do we have to do array copying instead of passing on the source array that the client sent to us?

So I have been googling about this OpenSSL heart-bleed thing and somehow sees that it is caused by the heartbeat extension which requires client to ping the server to show its aliveness and it all ...
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3answers
144 views

Best and safest API for a function which fills a buffer with variable-length data

I have a function which receives a buffer and returns some data in the buffer. The data can be smaller than the buffer capacity. Which is the best and safest API for this? int fn(void *buffer, ...
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1answer
770 views

What's the current best practice for C multithreading?

I've been a Java (and PHP) developer for most of my life, but will need to use C for my next project. I remember some basic stuff we did back in school with fork, pthread, semaphores, etc. but I'm not ...