Questions tagged [c]
C is a general-purpose computer programming language used for operating systems, games and other high performance work.
1,166
questions
-2
votes
1answer
53 views
Logically, is there a reason why ++i++ can not be a valid expression?
I had to increment my integer twice in a loop, so I thought I would try and be clever:
for (int i = 0; !sl.isEmpty(); ++i++) { ... }
++i++ however is not an assignable expression, at least in GCC.
...
0
votes
1answer
107 views
Architectural pattern for testable C code [closed]
I wrote a lot of software in C# and Python. I tried to make the overall architecture testable by using the "Clean Architecture" and Dependency Injection. This works well for C# (and python).
Now I ...
2
votes
3answers
110 views
Declaring Multiple Variables of the Same Type within a Function's Parameters
We've started looking at functions, and our homework requires us to include some simple ones in our programming. As we've left it a little late in the semester to explore functions, we're well-used to ...
0
votes
0answers
78 views
Searching/Hashing Wikipedia - at each position for keys 1..31 long, the fastest way?
A C coder here.
My wish is to find the best way to search words and phrases within the ever-growing English Wikipedia XML dump. As a first layer/step, hashing is the answer, yes?
The problem is that ...
3
votes
4answers
353 views
Alternative to nested-if on single return functions
I'd like to see if there has been any precedent on alternatives to nested-ifs--particularly for error-code returns. My workplace requires one return per function, so I cannot early exit. Here is some ...
4
votes
3answers
251 views
How to adhere to the Open Closed principle in a procedural language like C
In Robert Martin's seminal 1996 article "The Open-Closed Principle" he presents an example in C which does not follow the principle (the DrawAllShapes() method is not closed for modification):
enum ...
3
votes
1answer
73 views
Is a generic data structure customary for use in a self contained program, or can I duplicate source files?
I have a project that does some Dijkstra searches on a graph, I implemented a red-black tree and priority queue that I use for the nodes, however I also need the same data structures for other things ...
25
votes
7answers
6k views
Can abstractions and good code practice in embedded C++ eliminate the need for the debugger?
I am a C developer for an embedded system. YouTube has recently started recommending "C++ for embedded systems" talks. Having watched some of them, they pique my interest, but none of them answer the ...
3
votes
1answer
236 views
Avoiding Arrow Anti-Pattern in MISRA-C
For a safety-critical domain, with a code standard including the MISRA C 2004 guidelines, a "simple" piece of code becomes obtuse, chiefly because of the requirements both that all if() statements ...
10
votes
5answers
839 views
why aren't the platform specific integer types in C and C++ (short, int, long) deprecated?
TL;DR: Why isn't everybody screaming, "Don't use short, int, and long unless you really need to, and you very likely don't need to!"
I understand that, in theory, by using the types short, int, and ...
1
vote
1answer
116 views
Finding undefined behaviour in C for embedded system
I just started at a small company and there is a hot-needle-built software for micro controllers written in C which we are now starting to clean up to make it maintainable again.
Of course this goes ...
3
votes
1answer
109 views
Keep track of intializations done in a function
There is an initialization function in my app that does multiple inits. What is a good way to keep a track of inits done so that if init n fails all inits done before it must be cleaned up/de-init ...
0
votes
0answers
59 views
C++ client-server design
The context
I need to design a Client-Server(-Client) network in C++ that would allow an android application to communicate to a Raspberry Pi and back
I am running everything on linux environment(s) ...
3
votes
4answers
457 views
How to use Macros in Programming to make code faster, efficient and compact
Recently I was going through some of the solutions of the best competitive programmers in the world. I found out that those people use a template while writing the programs, preferably in C++.
I ...
42
votes
3answers
14k views
Why is the logical NOT operator in C-style languages “!” and not “~~”?
For binary operators we have both bitwise and logical operators:
& bitwise AND
| bitwise OR
&& logical AND
|| logical OR
NOT (a unary operator) behaves differently though. There is ~ ...
1
vote
1answer
106 views
How to eliminate transparent memory copy in runtime?
Despite various ways to scrub sensitive data in volatile memory (see Survive DSE or Zeroing buffers), programs tend to perform transparent memory copies (such as a Garbage Collection). The newly ...
3
votes
1answer
172 views
Managing error code and error message mapping
As part of a game engine I am writing in cython, one of the challenges I am facing is creating a consistent interface for error handling that works at the C and python levels of my code. I am ...
-4
votes
1answer
123 views
Is it really good idea to disable warning of C or Cpp? [duplicate]
When we are working on a big project of C or CPP, we are getting some warning. Therefore, we try to remove that warning because when we see compiler warnings that they make us feel dirty. When we ...
0
votes
2answers
79 views
Common header file for C++ and JavaScipt, redux
I've got a question closely related to this one. I'm cleaning up a colleague's mess, and I'm afraid that that means trying to work with a language -- JavaScript -- that I'm almost completely ignorant ...
2
votes
2answers
857 views
Can Rust replace the C or C++ programs in the Future? [closed]
I recently read an interesting Article that, due to a memory Overflow error Power system of Boeing will collapse and turns the Flight into a Flying Brick.
This is a low level memory Handling bug. ...
1
vote
3answers
355 views
Does the gcc optimize out local arrays the same way it would optimize out a local variable?
If I write this code in a function:
void func(void)
{
int x = 0;
int y = 3724832+x;
}
It would (probably) optimize the variable y out because it isn't being used. Even if I'm wrong about ...
0
votes
1answer
51 views
Thread-safe C library with OpenMP
I am writing a C library with routines I want to call from an external driver program using many OpenMP threads. The library will have a main container called lib_workspace, which will be used to do ...
-1
votes
2answers
169 views
malloc in caller, free in callee
Is it good practice to malloc in the caller function, and then free in the callee function?
Example:
int main() {
int *ptr = malloc(100);
foo(ptr);
return 0;
}
void foo(int *ptr) {
...
2
votes
3answers
260 views
Practical way to indicate an error from a function that returns a stuct instance?
Suppose I have a function that returns an instance of a struct with the following declaration:
struct data API(void);
Suppose also that there is a chance for the function to fail with an error ...
0
votes
1answer
103 views
C Function returning pointer to first element vs. a pointer to an entire array
Suppose I have an API function which returns a pointer to some memory, that is later to be consumed in an array-like manner. Suppose also that its size is known in advance, and that it's declared like ...
1
vote
1answer
136 views
Switching out implementation source files in C project
For simplicity, let's say I have the following C project structure:
src/
utils/
logger.c
logger.h
main.c
secondary_component.c
main.c starts with:
#include "utils/logger.h"
I would ...
0
votes
1answer
441 views
Should “NaN” default to SNaN or QNaN
I created a function to read floats (IEEE 754 binary 32-bit) from strings, for developers. I have everything finished and working perfectly, except i'm wondering if a user/or programmer enters a ...
0
votes
2answers
664 views
How to prevent 'global variables' in a big project?
With 'global variables', I mean
Variables on namespace level
Static data members in classes
Static variables in functions
In a big C++ project I would like to have a mechanism (like a compiler ...
0
votes
1answer
85 views
Sharing #define's between higher and lower layer. Where should shared types go? [closed]
Let's say I have a stacked 2 layer app (High Layer (HL) and Low Layer (LL)) that is implemented in C.
HL defines a few #defines.
HL calls a LL function with a parameter that takes values of the #...
1
vote
2answers
115 views
Reading problem of object-oriented concept about the book “Object-oriented software construction 2/e”
I've been learning object-oriented concept from this book, and stuck in a specified concept in the middle of chapter 6.
Because with no brief explaining beforehand, no one could understand my ...
2
votes
5answers
750 views
Advantages/Disadvantages of Compiling as Both C and C++?
So I've seen some C libraries written so that they compile without any changes with a C++ compiler, for example Lua.
What are some advantages and disadvantages of doing this?
A few basic ones I see ...
1
vote
0answers
29 views
MPI Derived Types and Portability
When using derived types in MPI for communication of data which is not contiguous in memory, the sequence of datatype-displacement pairs defining the derived type seems to be assumed to be the same ...
2
votes
2answers
306 views
A way not to forget to check for errors in C
As everybody knows, C allows us to write anything we want. There comes one big problem — we are the only who responsible to handle errors that comes from standard library functions and, therefore, ...
0
votes
0answers
46 views
How to analyse the throughput of multithreaded client server programs?
I am practicing socket programming in C language.
I have two codes - server and client (based on TCP) on two different laptops.
The server forks a new process for every new request.
For simulating ...
1
vote
1answer
138 views
How float data type stores number greater than 2^23? As Mantissa is only 23 bits
Can someone explain how floating point numbers are stored in C, as for 32-bit float, 1 bit is parity, 23 bits for mantissa and 8 bits for exponent. So for numbers greater than 2^23(still in the float ...
2
votes
1answer
132 views
How are primitives stored in memory
In my searching although this question seems to get answered a lot, the answers don't really cover what I want to ask.
I'm learning assembly and my question is, in higher level languages e.g C data ...
3
votes
2answers
918 views
What is the difference between a static library and an archive library?
In the comments of a recent answer, I equated a static library with an archive of compiled object files.
The response was that they are not the same, so what is the difference?
To clarify - gcc ...
0
votes
1answer
76 views
Types of errors that the primitive operators in C might be involved in
I am new to C and wondering how to properly build primitive functions in order to handle errors. Take for example the following function:
bool
testIfEqual(int a, int b) {
return a == b;
}
...
1
vote
1answer
164 views
Will Windows handle any memory not freed as well as threads not closed? [closed]
If I had an application that pretty much had a "fail-safe" as in, if I need to terminate the application quickly and not free the malloc'd memory, or close the threads that are running, would Windows ...
2
votes
1answer
50 views
Architecture design for Linux administrative interface
I've developed an IoT device utilising OpenWrt so my design needs run a on a shoe-string budget of resources.
I need to be able to push small amounts of data, up to 300bytes to my app on a very ...
2
votes
1answer
674 views
Why did Java and C sharply dip in popularity around 2017 in the TIOBE index? [closed]
The TIOBE Programming Community Index shows Java and C dramatically falling in popularity between late 2016 and mid 2017 before rebounding by mid 2018. What is the cause of the volatility?
Source: ...
-2
votes
2answers
110 views
Should I call a callback for an event triggered by a developer?
I'm designing an API for a stream-processing library. The library will process a stream provided by the user and will transition between states based on the data in the stream. The state transitions ...
3
votes
3answers
842 views
How does a compiler work when it's not directly compiling to machine code
I know the compilation process goes with this flow:
source -> parse -> AST -> intermediate code -> assembly -> machine code
and in the case of Java you will have bytecode which is ...
0
votes
1answer
121 views
Is it possible to swap out programs displayed in stdout?
I would like to write a program in C that forks then execs three different processes.
Afterwards, two of the programs will be suspended and only one of the three will be outputting to stdout. Is is ...
0
votes
2answers
56 views
Architecture/design for reading incoming data and distributing it across program
This may be a broad question but I have not been able to find an answer.
In my program I am communicating to a device over serial communication. The data coming through is binary, and formatted with ...
-1
votes
1answer
138 views
static, dynamic analysis - what mistakes were made in the code?
A software company develops software packages for commercial animal
farming. A special function in C calculates the daily amount of feed
for different kind of animals dependent on their bodyweight....
1
vote
3answers
435 views
Does each process have it's own section of data, text , stack and heap in the memory?
I have created the above picture to illustrate my question.
Is there a section within memory (lets say from address 0x1 to 0x15) that all processes use to place their text segment in (left figure), ...
5
votes
2answers
299 views
Why use multi-purpose getters that take an enum value, rather than separate getters?
I'm designing a C API which will have about a dozen getter functions for various values. Something like:
bool getSomeBool();
bool getSomeOtherBool();
...
int getSomeNumber();
int getSomeOtherNumber();...
46
votes
3answers
11k views
Why do we still grow the stack backwards?
When compiling C code and looking at assembly, it all has the stack grow backwards like this:
_main:
pushq %rbp
movl $5, -4(%rbp)
popq %rbp
ret
-4(%rbp) - does this mean the ...
0
votes
1answer
101 views
Chain function calls which return error codes or 0 on success in C [closed]
I used to call functions which returns int error code or 0 on success like this:
int tmp = function_a() ?:
function_b() ?:
function_c();
if (tmp)
handle_error();
Now I'm ...
