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

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1answer
111 views

How implement a doubly linked list using single pointer inside? [closed]

struct{ int value; int *pointer; } I want to make doubly linked list using the above structure.
1
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3answers
256 views

Including extra headers that I do not really need

I always wondered what are the effects of including not needed headers to the final executable once compiled. In my code some times I may included many different headers that I do not need (or I used ...
2
votes
1answer
264 views

Quickest sorting algorithm for sorting a low number of integers

I am making a program on my spare time that I want to run as quickly as possible. The program is written in C. A large set of the procedures operate on pointers to 7 integers that are sorted by their ...
25
votes
7answers
3k views

Is it good practice to rely on headers being included transitively?

I'm cleaning up the includes in a C++ project I'm working on, and I keep wondering whether or not I should explicitly include all headers used directly in a particular file, or whether I should only ...
1
vote
1answer
74 views

Holding of files being edited in a text editor

I'm writing an implementation of Ex (hopefully Vi eventually) as a personal project. I need to somehow store an identifier for the file associated with each buffer. In terms of security/race ...
0
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0answers
167 views

In-place merging of sorted intervals in an array?

So I have code producing k sorted intervals in an n-sized array. What I'm brainstorming is the possibility of in-place merge of these intervals into a single sorted interval/array. The problem is ...
5
votes
2answers
201 views

When should a trig function, with a degree argument, return -0.0?

In creating trig functions my_sind(d), my_cosd(d), my_tand(d), that used a degree argument rather than a radian one and provided exact answers at multiples of 90, I noticed that the result was ...
0
votes
3answers
158 views

Alternative to printing debug information to stdout\stderr [duplicate]

I currently have a long running application on an embedded Linux environment and all debug messages are currently being outputted to stdout using printf. This isn't ideal for special users who ...
8
votes
1answer
270 views

Do any notable C extensions include integer types whose behavior is independent of machine word size

An interesting characteristic of C compared with some other languages is that many of its data types are based upon the word size of the target architecture, rather than being specified in absolute ...
2
votes
2answers
391 views

Generics in low level languages

I'm developing a language like Vala and OOC that compiles back to C. This means that, eventually, every feature needs to be adoptable to C code in some way or another. Generics is one of the features ...
7
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2answers
239 views

Autoreleasing objects in Reference Counting Systems

I'm experimenting a bit in C and I'm trying to implement my own Reference Counting System. I've mainly worked with Objective-C in the past but AFAIK autoreleasing objects is something that is unique ...
1
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0answers
65 views

Is conversion from C/C++ to Verilog/VHDL for FPGA a derivative work? [duplicate]

Say I have a C/C++ software licensed under GPL that gets converted into hardware design. By this conversion I mean that the exact functionality of the original software is being programmed into an ...
3
votes
6answers
458 views

Explicitly define enum values, even if the default value is the same?

There are times when an enum's values are important: it is not necessary for them to be unique, they also need to have specific values. In such cases, should the values be explicitly defined, even if ...
1
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2answers
99 views

Return equal occurrence of char in a list of strings

I have an array of strings ["abb", "bbxxaa"]. I would like to print all characters that occur equal times in each index so in above case I would print bb because they occur twice in both indexes and ...
0
votes
2answers
234 views

C Linked List Implementation Pointer vs. Pointer-to-Pointer Consistency

To get some practice in C, I'm writing some basic functions for operating on a linked list of ints. I started out with functions that accepted as a "list" a pointer to the head node. Now, I find ...
2
votes
2answers
88 views

API to get data, caller may not know how much? How to allocate buffer size

I am writing a C API for retrieving data from a hardware device. The data will be returned as a string with approximately 30 bytes of text per item. The problem is there may any number of items. ...
9
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5answers
1k views

When does it make sense to compile my own language to C code first?

When designing an own programming language, when does it make sense to write a converter that takes the source code and converts it to C or C++ code so that I can use an existing compiler like gcc to ...
3
votes
3answers
421 views

Separating Code into Smaller Files in C

I am in the process of cleaning up my code and making it easier to maintain. I am doing this by turning my 5000+ line file into separate smaller files. I have successfully created separate source and ...
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votes
1answer
388 views

Illustrate Meaning of : gcc -g programName.c

To debug a C program using gdb effectively it is required to compile it first using the command: gcc -g programName.c otherwise on using simply gcc programName.c and running we are unable to ...
1
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1answer
223 views

What are the current (2014) naming conventions in C for file names? [closed]

This is about C, not C++. Googling this brings this result up immediately: https://www.doc.ic.ac.uk/lab/cplus/cstyle.html#N10081. In that article, the authors are saying very clearly that all source ...
1
vote
2answers
381 views

Given a number X, how do I find from an array of numbers, a unique combination that adds up to X and has the lowest sum of squares?

Given the number 15 and the array [1, 2, 3, 4, 5, 6] Possible combinations (sum=15) would be: [1, 2, 3, 4, 5] [2, 3, 4, 6] [1, 3, 5, 6] [4, 5, 6] Their respective sum of squares would be: 55, 65, 71 ...
1
vote
2answers
485 views

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 ...
1
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5answers
125 views

Does it make sense to have a separate init function?

I'm created an opaque type and I have two options for its management. The first looks like this: type_t *a = type_init(); int err; err = type_do(a, "foo", "bar", FLAGBIT1|FLAGBIT2, NULL); if (!err) ...
1
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1answer
1k views

The advantage of using __attribute__((aligned( )))

I found in more than one SIMD program the instruction __attribute__((aligned(16))) . When I looked for an explanation I found The keyword attribute allows you to specify special attributes of ...
7
votes
5answers
659 views

Undefined behavior, in principle

Whether in C or C++, I think that this illegal program, whose behavior according to the C or C++ standard is undefined, is interesting: #include <stdio.h> int foo() { int a; const int ...
1
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3answers
217 views

How to abide the “allocate in caller” rule when the size is computed in the callee?

Let's say we have an opaque type handle_t that is managed through a simple interface with functions such as: handle_t *handle_init(void); int handle_do(handle_t *); void handle_free(handle_t *); ...
4
votes
2answers
125 views

Defining error codes

We are designing an error-handling framework for a cryptographic library written in C. The approach we are taking is that relatively few errors are propagated back to the user since on most occasions ...
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votes
1answer
211 views

Ambiguous If-else nested block in C without braces [closed]

Consider the following code in C: if(34) if(0) printf("Stat1"); else printf("Stat2"); Here,the first if condition is true,while the second if condition is ...
1
vote
1answer
472 views

Polymorphic engines in C and/or C++ [closed]

I stumbled across polymorphic engines and I don't know anything about them. However, I am curious about how they are written. Every example that I've looked up writes them in assembly, my assembly is ...
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votes
1answer
99 views

Buffer-overflow vulnerabilities that a static code analyser won't pick up [closed]

I'll use FlawFinder in this example. FlawFinder is a static code "analyser" tool that examines C/C++ source files and outputs warnings/hits if a vulnerability was identified. The way it does this is ...
3
votes
2answers
336 views

On concatenating adjacent string literals

C and C++ compiles adjacent string literals as a single string literal. For example this: "Some text..." "and more text" is equivalent to: "Some text...and more text" In other languages like C# ...
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votes
1answer
119 views

Uniqueness of for loop [closed]

How does the for loop function is implemented so that it can accept ; as parameter separator rather than , which is trivial in normal functions.
8
votes
5answers
734 views

Are C static libraries frowned upon? [closed]

There are 2 arguments for having shared libraries: It helps reduce disk space. When a shared library is updated, all the binaries depending on it get the update. There is mainly one drawback for ...
1
vote
2answers
233 views

Microchip XC8: How to pack code against an upper limit?

I have a project for a PIC16F1454 that needs some custom linking. Basically, I've separated my code into two parts that can be downloaded separately in the field and thus update (almost) all of the ...
4
votes
1answer
625 views

Why did GCC switch from Bison to a recursive descent parser for C++ and C?

Was there a language change that required it or some practical reason why Bison was no longer appropriate or optimal? I saw on wikipedia that they switched, referring to the GCC 3.4 and GCC 4.1 ...
2
votes
2answers
203 views

In which stage of compilation is “typedef” resolved by the compiler?

There are different stages of compilation Such as Preprocessing stage Syntax analysis Semantic analysis Intermediate Code generation Machine Code generation Optimization Linking My question here ...
3
votes
1answer
146 views

How to fix legacy code that uses <string.h> unsafely?

We've got a bunch of legacy code, written in straight C (some of which is K&R!), which for many, many years has been compiled using Visual C 6.0 (circa 1998) on an XP machine. We realize this is ...
5
votes
7answers
3k views

Why do we need to include the .h while everything works when including only the .cpp file?

Why do we need to include both the .h and .cpp files , while we can make it works with making just a .cpp file and then including it . For example, Creating a file.h containing declarations, then ...
19
votes
12answers
6k views

Why does void in C mean not void?

In strongly-typed languages like Java and C#, void (or Void) as a return type for a method seem to mean: This method doesn't return anything. Nothing. No return. You will not receive anything from ...
0
votes
1answer
74 views

Macro guard in Objective-C

I have noticed that many famous libraries written in Objective-C (eg. AFNetworking) use the macro guard inside their header files. Im aware that the #import directive, which works exactly like ...
-2
votes
1answer
275 views

What are steps in making an operating system in C ? [duplicate]

I am trying to make an my own OS. This is for educational purpose only, so that I get to understand the internals as well as get a good idea of low level programming. I have some prior application ...
1
vote
2answers
222 views

Is goto to improve DRY-ness OK? [duplicate]

My code has many checks to detect errors in various cases (many conditions would result in the same error), inside a function returning an error struct. Instead of looking like this: err_struct ...
0
votes
1answer
113 views

comparison of an unsigned variable to 0

When I execute the following loop : unsigned m; for( m = 10; m >= 0; --m ){ printf("%d\n",m); } the loop doesn't stop at m==0, it keeps executing interminably, so I thought that ...
3
votes
3answers
182 views

Why are packed structures not part of the C language?

Every C compiler offers the option to "pack" C structures (e.g. __attribute__ ((__packed__)), or #pragma pack()). Now, we all know that packing is required, if we'd like to send or store data in a ...
-4
votes
1answer
342 views

Calculate Pi to N number of places [closed]

I am trying to work out how to calculate Pi to N decimal places, I think the default DP's for a float/double is 5 and then you have setprecision() however these are obviously inadequate, I need ...
2
votes
1answer
186 views

How to store satellite data in C data structutres

I've been reading through Introduction To Algorithms 3rd Ed, and am really enjoying the material; however, I am having difficulty in implementing some practical situations. It's not the theory, or ...
1
vote
3answers
678 views

Reconstructing a huffman tree using minimal information in the header

I'm writing a huffman encoding program in C. I'm trying to include the least amount of information in the header as possible, I know the simplest way to decompress the file in the header would be to ...
3
votes
3answers
588 views

C/C++: Which conversion warnings make sense in practice?

C/C++ implicit conversions can cause bugs. Here's one example: int foo, bar; scanf("%d", &foo); scanf("%d", &bar); float foobar = foo / bar; If I input 7 and 2, it's not 3.5 as expected - ...
6
votes
2answers
487 views

C programming practice, passing a pointer to a function [closed]

Consider the following C function which takes as argument a string, which is then stored inside a struct: struct mystruct* usestring(char* string) { struct mystruct *struct; struct = ...
1
vote
2answers
328 views

Implementing a simple controller in embedded C

Is there a known method or pattern to implement a simple controller for an MVC design in pure C or the switch case approach is the standard? Background : I have an embedded application and I'm ...