Questions tagged [c]
C is a general-purpose computer programming language used for operating systems, games and other high performance work.
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Finding header files
A C or C++ compiler looks for header files using a strict set of rules: relative to the directory of the including file (if "" was used), then along the specified and default include paths, fail if ...
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Is there any merit to using `union` to create an alias?
I've inherited a bit of code and saw something new. They have a data structure definition out in a .h file, and in various local files they'll declare:
union globalStructOstuff localVar;
Is there ...
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Naming convention for functions that mutate arguments vs creating a new object
Take the following signature
BigInt* addBigInt(BigInt* arg1, BigInt* arg2);
Traditionally, the safest way to implement this function would be for it not mutate the arguments, and would necessarily ...
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malloc on different platforms
I am testing a red-black tree implementation (repository) and I find that with Windows 10 and gcc, malloc starts returning NULL after inserting approx. 50 million nodes but on Linux it works at least ...
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How useful is JNI in android?
In java/android we can call code written in the c/c++ language for execution speed advantage. I have heard of Ahead Of Time compilation which (as far as i know) compiles the entire application to ...
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Protecting Structure from corruption
I am developing a safety critical embedded system and I am programming in C.
We have a set of const structure declared in memory and they hold some critical data. I want to make sure that any of ...
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Equivalent of C library functions
In C, almost everything requires a function. What nags me is that I don't know exactly what's going on. If there was no msvcrt.dll file, my C programs would all break because that's where all the ...
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Kernel operation
I'm trying to grasp the concept of an operating system at the moment (on Unix-like machines)
The kernel is the process with PID 0. Of course the Kernel is not really "just another process" because a ...
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Complex iterators in C
note: this was originally asked on SO.
Part of my current project involves iterating over sequences that don't necessarily exist. For example, I have something similar to a relational database in ...
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(almost) Pure C instead of C preprocessor [closed]
Why isn't (almost) pure C used instead of the C preprocessor?
Sure I understand it would be a little more verbose. For example:
#define PI 3.14159
If we had regular C as preprocessor language, the ...
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Infinite while loop CPU usage
I'm coding an script in C, which is going to check constantly an array of events, the idea is to check if the Date and time of certain event is equal to de current time and trigger something, i'm ...
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Evaluation order of the expressions
The C Programming Language by K & R states that C, like most languages, does not specify the order in which operands of an operator are evaluated. (The exceptions are &&,||,?: and ','). ...
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Send stdout or stderr to a new thread
For performance issue I want the logging send to a new thread.
While the main program can work, the new thread can write the error or other messages to a file without effect to the main program. How ...
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How far is the trail from Java to C / C++? [closed]
I want to find out how easy or hard the transition to C / C++ is for a mid-experienced Java programmer.
I've already read the questions about "C++ for Java Programmers" and "Is it necessary for Java ...
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Should functions depend on other functions?
Suppose I have a function to log error messages printError(). Suppose I have another function which might throw an error, doSomething(). Should doSomething() implement its own error logging or depend ...
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Declaring functions using macros?
Is it generally encouraged or discouraged to create a pre-processor macro in C, that facilitates the creation of many functions with the same signature (differing only in name). For instance, instead ...
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What's the best architecture to mix C code and a ASP Classic website
I have to create a real-time display. On this display I have to get the numbers from an existing business logic component (written in C) and display these Live on a classic ASP-page (legacy app).
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Implement inheritance in C
I was working with GTK in one of my projects and I noticed that the library supports inheritance. As you can type-cast a child struct to its parent struct and vice versa. Other than GTK I've never ...
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How to compare C and CUDA performance fairly?
I have developed a CUDA code that is a reimplementation of a (CPU only) C code.
I would like to benchmark the performance of these two programs. I am wondering how to do benchmarking well in this ...
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Can a data hold multiple values?
I'm a beginner and I'm following a course on C programming.
In my book,a variable is defined as a memory space that stores a single unit of data (datum).
Is a data structure considered to be a single ...
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Would it be a good idea to use variadic functions in a C API as a means of preserving the ABI?
Say you're designing a C API, and one of your big concerns is ABI stability (it's going to be deployed as a shared library, or whatever).
You have a function exported
int foo_bar(int a, int b, int*...
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Using GPLed headers in LGPLed library
For a specific device there exists a Linux kernel module. This module only initialized the device and provides control mechanisms to user land via ioctls and mmap. To use this the device properly one ...
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Best way to use a C++ style api from a C style file compiled in C++
I am working a in a Telecom company. We have some code generation tools that generate C style files based on a MIB definition. We compile them with C++ though. It boils down to the fact that these ...
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In C, are large 'pointer chains' bad for performance or code cleanliness?
The following for example:
i = readString(&packet->data.play_server.updatesign.line1, pbuf, ps);
It has a large amount of nested structs/unions. Is this generally frowned upon in code ...
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What method for storing a text file in memory (c not c++) would allow me to open any format(UTF-8, Binary, etc) and a file of any size?
My first thought here is to use a dynamic array, but I am looking for something better.
Currently I have the text files open into "chunks". Every word or group of spaces makes up a "chunk". Then I ...
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Are there any problems with defining a single-source "module" in C using conditional compilation to separate the "header" from "source"
I'm writing a project that I want to keep small in the sense of being very densely-coded and a single source file.
But it's growing large enough that navigating the file is becoming tiresome, so I ...
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C Module - Where to put prototypes and definitions that do not belong to the public interface?
Since I am mainly an Electrical Engineer, forgive me if I am somewhat off with some terminology.
I am currently programming a display driver/interface module. And like so many times before, I have ...
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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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"continue" and "break" for static analysis
I know there have been a number of discussions of whether break and continue should be considered harmful generally (with the bottom line being - more or less - that it depends; in some cases they ...
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Do simple accessors and mutators benefit from commented block headers?
Short Question
Is it necessary to add the function header comments for simple accessors and mutators?
Example
u8 OBJ_get_state_x(void) {return obj.state_x;}
void OBJ_set_state_x(u8 x) {obj....
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What pitfalls and gotchas commonly occur when beginning with Parallel and Concurrent Programming with C? [closed]
It roughly three weeks I will be taking a Parallel programming class that is taught using C for the assignments. I have a fairly strong interest in the subject at present and my C skills aren't ...
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Using a preprocessor macro to wrap functions?
I have multiple use cases where I need to call an "entry" function, do a bunch of stuff, and then call an "exit" function. (In my case, "entry" is enabling a chip select ...
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C programming - Advantages and disadvantages of using opaque pointers for structure handling
Which are the main advantages and disadvantages of me using opaque pointers for all my structures? I have been thinking about using this approach and here are some trivial thoughts that I have:
...
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Wrapper function or aliasing with a union?
I have a structure that might have 2 more members depending on a preprocessor variable.
struct foo {
int m1;
// ... (other members)
#ifdef MORE_MEMBERS
int m2;
int m3;
#endif
}...
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Is there any technical reason to typedef void? [closed]
No opinions, please. Is there any technical reason to typedef void?
My current company and my last both have typedef void XYZ_void; where XYZ is the project name.
I can understand a typedef for ...
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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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C Equivalent of Perl Unpack & Pack
I have some perl code that uses pack and unpack to transform the data in a way that I don't understand.
$unpacked_data = pack('b*', join('', unpack('(b7)*', $packed_data)))
Where $packed_data = a ...
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Is the Leptonica implementation of 'Modified Median Cut' not using the median at all?
I'm playing around a bit with image processing and decided to read up on how color quantization worked and after a bit of reading I found the Modified Median Cut Quantization algorithm.
I've been ...
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Source control workflow for managing a software platform
I'm in charge of a software platform, written in C, that is used to provide a variety of projects to clients. I am trying to improve the workflow for people using this platform, and looking at ...
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API for data structure with indices, size_t vs int?
For a data structure with indices (e.g. an array list, a dynamic array, etc...), should the indices be of type size_t or int? Is there a clear reason to use one over the other?
fooGetByIndex(struct ...
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State propagation(bottom-up) in multi-walk tree
Using the Tree representation(mentioned below),
typedef enum {Running, Warning, Critical}Status;
struct TreeNode;
typedef struct List{
int childCount;
struct treeNode **childList;
}List;
...
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How to communicate between cooperative tasks "first me, then you"?
I am in the final stages of development of a simple embedded system. The device performs PID coefficient estimation and then instantiates a PID controller with the estimated coefficients.
The ...
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Parallel Threading in Multi-Language Software?
I'm developing a software that contain many modules/Daemon running in parallel manner, what i'm looking for is how to implement that, i cannot use Thread because some of those modules/Daemon are ...
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Shared FIFO file descriptor
is ok to open fifo with one FD and share it with multiple threads?
or is it better to have multiple fds opened for the same fifo and share these fds with the threads?
BTW, I'll be doing write and read....
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Is Operator Overloading supported in C
When I read about the LCC (Windows) compiler, I found out it has the implementation for operator overloading.
However, after a bit of Googling, I've confirmed that operator overloading isn't ...
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When should I use static variables with primitive types?
Recently I came across the question NSString: Why use static over literal? and in the comments arrived a new question.
In Objective-C there some "special" types that are just maps to C primitives. ...
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Publisher-Subscriber architecture with central registry
Problem description
Publisher-Subscriber architecture with a central registry where agents can either promote their capabilities or search for a given capability.
The project must be developed with ...
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Embedded software architecture - What is the difference between DAL and HAL?
I'd like to know what the difference is between hardware abstraction layer (HAL) and data abstraction layer (DAL) when speaking about embedded software. I might have the abbreviations wrong though...
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What tasks does a memory barrier enforces other than preventing the re-ordering of instructions?
I know that a memory barrier prevents the re-ordering of instruction from before to after and from after to before the memory barrier, for example if I have the following instructions:
instruction 1
...
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How does a dynamic library's references to a global variable get translated once in the running app?
If a dynamic library exports the address to a global variable defined within the library, how are accesses to that variable translated during dynamic linking so that a running application can interact ...
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