C is a general-purpose computer programming language used for operating systems, games and other high performance work.
-3
votes
0answers
47 views
adding manually written headers in C language [migrated]
I'm writing a code for a radio, which contains many child functions and header functions. I've created two headers "simulation_params.h" in which the simulation parameters can be changed, and ...
-1
votes
0answers
40 views
In C language fscanf reads last number twice [migrated]
I have written this code to read from an input file and display the numbers:
#include<stdio.h>
int main()
{
int i;
FILE * f;
f=fopen("inputA.txt","r");
while (!feof(f)){
fscanf(f, "%i", ...
-3
votes
0answers
19 views
C code link edit error in Visual studio 2003 [migrated]
I have installed Visual Studio 2003 in my Windows 7 system and started compiling the C code by using the NMAKE functionality. I have compiled the code with out any issues, but during the linking ...
0
votes
1answer
90 views
dynamic memory allocation in c language
i'm using dynamic memory allocation in c programming..
supposing i've program like this
void main()
{
int *C;
int sum;
-----------
statements
-----------
test(C,sum);
}
void test()
{
---------
...
-2
votes
0answers
63 views
Why goto statement is not considered as loop in C language [duplicate]
Printing the numbers 1 to 5 using a for loop is possible, and using goto statement also is possible, but for is considered a loop and goto is not considered as loop. Why is this?
-1
votes
0answers
54 views
Problems with printf() on AVR in C with floating-point [migrated]
I've been getting back into C, and I've been working on an 'academic' exercise to sharpen some old skills again. My project revolves around the rather simple process of generating sines. I started out ...
-1
votes
0answers
91 views
When learning programming, is it better to start from the oldest language? [closed]
Many years ago, we were taught how to operate and develop simple programs using Turbo Pascal. Now, I would like to learn more about programming languages. I know that I'm starting off from a vague ...
-2
votes
0answers
28 views
getchar gives output in incorrect order. [closed]
The program should give output in the following way:
Enter a character
g
Successfully entered!
g
#include <stdio.h>
int main() {
int c,d ;
printf("Enter a character\n");
...
2
votes
2answers
56 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. ...
-3
votes
0answers
39 views
C Programming reading file [migrated]
I am trying to write a very simple code to read a file. However in that file I have M_PI/2, which is pi/2. When my code reads that file it spits M_PI/2 as 0.000. How do I make my program to make it ...
5
votes
4answers
427 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
361 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 ...
-3
votes
1answer
88 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 ...
0
votes
1answer
141 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
104 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
164 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 ...
-2
votes
2answers
128 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 ...
0
votes
3answers
97 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
vote
1answer
60 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
459 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
3answers
187 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
93 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
126 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
187 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
66 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
161 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# ...
-2
votes
1answer
112 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
540 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
95 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
247 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
114 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
126 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
1k 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
48 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
169 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
196 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
106 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
115 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
128 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
143 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
85 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
196 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
351 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
127 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
124 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
166 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
132 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
230 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 ...
5
votes
1answer
430 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 ...
