C is a general-purpose computer programming language used for operating systems, games and other high performance work.
0
votes
0answers
94 views
What does “hardcore C programming” really mean? [on hold]
I've seen the term "Hardcore C programmer/programming" used by some programmers specialized in C. Searching online didn't yield any definitions what this adjective really means and how the term varies ...
1
vote
2answers
90 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
132 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 ...
-3
votes
0answers
34 views
Output of a program [migrated]
{
int a;
a=4;
cout<<a++<<++a;
}
The output of the above C++ program is 56 but why it is not 46
As a++ first print the value then increment a.
-2
votes
2answers
119 views
Returning void from a function specified to return int [closed]
int count_to_ten ( int count ) {
/* we only keep counting if we have a value less than ten*/
if ( count < 10 ) {
printf("%d",count);
count_to_ten( count + 1 );
}
return;
}
int ...
-2
votes
0answers
139 views
How to call a function with argc & argv? [migrated]
I'm currently trying to create a GUI for an existing command line program using QT, as a learning exercise.
The original code was written in c, and I have included the c wrapper for the c++ bit. I ...
0
votes
0answers
6 views
Pointer to Array of Strings as CONST? [migrated]
i program a application with mikroC PRO for AVR on the Hardware mikromedia for XMEGA.
I have different languages to show on a TFT Display.
I must switch the languages at runtime.
This works the ...
0
votes
3answers
90 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) ...
-6
votes
1answer
81 views
C program for Tree Traversal without Recursion [closed]
I want to write a C function for Tree Traversal without Recursion. The program that involves recursion is too simple, I want to do the same thing without recursion. I know the algorithm but couldn't ...
1
vote
1answer
45 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
...
6
votes
4answers
418 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
vote
2answers
121 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
84 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 ...
-2
votes
1answer
120 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 ...
0
votes
1answer
167 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 ...
0
votes
1answer
62 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 ...
-2
votes
0answers
25 views
Problems Initializing a Struct at Declare Time Using Char Pointer [migrated]
I am trying to declare and initialize a struct using a char* pointer. Compiling the code below fails if I do anything but
thing things[] = {{3,300},{4,*text}};
Linux gives me a core dump when it ...
3
votes
2answers
150 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# ...
0
votes
0answers
49 views
Basic logical operator question [migrated]
#include <stdio.h>
int main()
{
int k=5;
if(++k < 5 && k++ / 5 || ++k <= 8)
{
printf("%d",k);
}
return 0;
}
Why is the output 7 and not 8?(I am a ...
-2
votes
1answer
109 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
531 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
79 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 ...
3
votes
1answer
216 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 ...
-1
votes
0answers
12 views
Problem with C code. Raspberry PI, HD44780 LCD [migrated]
I have been writing a program for interfacing a raspberry pi with a HD44780 LCD.
The code I have wrote does not seem to initialise the display, from the datasheet as far as I can tell I am doing the ...
2
votes
2answers
107 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
123 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 ...
3
votes
7answers
982 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 ...
18
votes
12answers
5k 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
43 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
162 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
192 views
Is goto to improve DRY-ness OK?
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
105 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
113 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
111 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
130 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
74 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 ...
2
votes
3answers
187 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
333 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
117 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 ...
0
votes
2answers
115 views
boolean operations in C using bitfields
I am trying to implement boolean data type in C. Basically, I am working with sets.
The following code can be used to access each bit but I am unsure whether I can represent sets using this method.
...
1
vote
1answer
164 views
What is this boolean law?
A friend of mine has shown sometime ago the name of the below boolean technique/law but I forget that name unfortunately. Does someone know what it's called?
example in C language:
!(a || b)
It's ...
-1
votes
2answers
124 views
Reading assembly useful for insights when writing C/C++? [closed]
While in most cases its not necessarily, recently I have taken to reading the generated assembly of my C code every so often, when I'm curious as to the kinds of optimizations my compiler is making. ...
5
votes
2answers
226 views
Processor architectures for testing C/C++ portability
Currently I'm working on a C/C++ code-base which is fairly portable, it can compile on most Unix like systems as well as MS-Windows (MSVC), using various popular compilers.
Previously I've found ...
4
votes
1answer
358 views
Why does C use the asterisk for pointers?
I'm just now learning about C.
I find it odd that the creators chose the asterisk (*) as the symbol for pointers rather than a symbol that actually looks like a pointer (->).
Considering how ...
20
votes
3answers
3k views
Why Increment Pointers?
I just recently started learning C++, and as most people (according to what I have been reading) I'm struggling with pointers.
Not in the traditional sense, I understand what they are, and why they ...
1
vote
2answers
72 views
Is there a stricter strtoull() in any ubiquitous C library?
I want a function that will interpret a string as a strictly unsigned integer, failing when the string overflows, represents a negative number, or does not represent a number.
strtoull() does set ...
-3
votes
1answer
107 views
Implementing keyword “const” [closed]
A constant pointer is a pointer which points to a fixed memory location throughout.The question is how do you ensure that this behavior is ensured without using the keyword constant while declaring ...
1
vote
4answers
166 views
What should I do and know before I start writing C? [closed]
I have a college degree in CS, and learned about Java and OCaml. Java was used as introduction, and in most CS classed, except the theoretical ones. OCaml was part of learning a different programming ...
2
votes
2answers
154 views
Why do binary files load quicker than alphanumeric text files?
I've noticed that when I load/store large data files in a binary format, the program runs much faster than if I load data from an ASCII encoded file.
Why is this the case? The data in my case is ...
1
vote
1answer
192 views
Which is the more testable C function implementation?
I write code in C. I have been striving to write more testable code but I am a little
confused on deciding between writing pure functions that are really good for testing
but require smaller functions ...
