New answers tagged c
1
vote
Bellman-Ford optimisation in C with Shortest Path Algorithm (SPFA) and Small Label first (SLF)
Concerning *alloc() discussion, (not a major issue with OP's code)
Recommend:
No cast
Size to the referenced object, not type.
Check result
Lead any size ...
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3
votes
Accepted
Tar implementation
What’s the Deal Here
Tail recursion is an extremely useful pattern. You’d normally use it to transform a loop into an equivalent function that calls itself. All the state that carries over from one ...
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7
votes
Tar implementation
The recursion here is not tail recursion.
A tail-call is one where no further processing is needed between the called function's return and that of the calling function (this means that the current ...
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5
votes
Bellman-Ford optimisation in C with Shortest Path Algorithm (SPFA) and Small Label first (SLF)
We're missing a lot of includes. At least the following standard headers:
...
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12
votes
Bellman-Ford optimisation in C
for (uint _ = 0; _ < nb_nodes - 1; _++)
Maybe this was python code translated into C?!?
Repect the norms of the community.
Even though ...
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6
votes
Bellman-Ford optimisation in C
A few pieces of advice you can consider:
As far as I'm aware, documentation comments are conventionally immediately before the declaration, not between the signature and the body of the ...
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3
votes
Compute the sum of even numbers between two values
Just some corner thoughts
Overflow
sumOnlyEvenNumbersInRange(INT_MAX, INT_MAX) incurs signed integer overflow with ...
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6
votes
Compute the sum of even numbers between two values
The Math
Pardon if you already know this, but: the usual way to solve for a closed-form solution for a series like this is to note that the sum of a series that grows at a linear rate will be ...
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8
votes
Accepted
Compute the sum of even numbers between two values
The first implementation mixes integer and floating-point arithmetic. I definitely would avoid that.
The other two versions both use >> on a signed type (<...
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5
votes
In-place recursive quick sort in C
Still looks pretty good!
Beware Mixing Signed and Unsigned Integers
Because of the default type-conversion rules, you could get bugs like the famous 3U < -1. ...
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4
votes
Accepted
Damerau-Levenshtein distance performance improvements
Please write this
int min_int(int arr[], size_t size)
{
assert(size > 0);
That will avoid
UB,
and give the caller a nice diagnostic if he messes up his
...
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4
votes
In-place recursive quick sort in C
No naked loops
Every loop implements an important algorithm, and therefore deserves a name. In your case, the loop
...
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3
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In-place recursive quick sort in C
General Observations
Good use of the current C programming standard. The code is basically well written, but variable names could be improved, at least in main().
I ...
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2
votes
Run command in a child process
Unnedded -1
No need to subtract 1.
The fgets function reads at most one less than the number of characters specified by n from ...
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1
vote
Solution to Codejam 2021 1C (Closest Pick) in C
We don't really need to store and sort the entire list of gaps. We're just interested in the largest gap we can cover with two tickets (that's max_gap_size) and ...
- 67.7k
4
votes
Solution to Codejam 2021 1C (Closest Pick) in C
Common mistakes
This echoes @Haris Enable more compiler warnings:
As part of a code review, when such trivial errors are found so readily, it casts an overall disappointment on code.
Avoid the 3 ...
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3
votes
quadratic probing hashmap and its time efficiency
Minor stuff:
IsPrime(1) is usually considered false
...
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4
votes
Run command in a child process
Use posix_spawn
Or possibly posix_spawnp. It’s in the POSIX standard precisely to take care of this. You don’t need to reinvent ...
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3
votes
quadratic probing hashmap and its time efficiency
Quadratic probing uses as the \$i\$th offset from the first probe index \$\pm 1^ic_2i^2+c_1i+c_0, c_2\ne 0\$ with parentheses inserted as deemed useful.
...
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7
votes
Run command in a child process
Code risks invoking undefined behaviour:
if (argc != 2) {
printf("Usage: %s <0|1|2|3>\n", argv[0]);
return EXIT_FAILURE;
}
Dereferencing <...
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5
votes
Run command in a child process
We need to enable more compiler warnings - these problems are trivially fixed:
...
- 67.7k
4
votes
Accepted
Solution to Codejam 2021 1C (Closest Pick) in C
Enable more compiler warnings
GCC reports some warnings:
...
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3
votes
quadratic probing hashmap and its time efficiency
General Observations
Interesting question! As the comments show, a lot of room for learning!
Consistency! Some header files are using Doxygen Comments, other headers are not, some header files don't ...
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6
votes
Max-heap implementation in C
The biggest issue I see here, and is not yet commented on, is the call to realloc for every insertion. When you remove an element from the heap, the ...
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1
vote
Create a structure to store student data and display all the records in the array
Additional thoughts to add about void AssignGrade(Student s[]):
Avoid the hole
As is, OP's code "works" with ...
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5
votes
Max-heap implementation in C
Avoid FP math for an integer problem
floor(log2(max_heap->size)) is overkill and at some level risks incorrect results with less than ideal FP functions. A ...
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1
vote
0
votes
Create a structure to store student data and display all the records in the array
I'm just going to look at the AssignGrade() function.
...
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10
votes
Max-heap implementation in C
General Observations
Since this might be a set of library routines, it might be a good idea to move all the heap related functions to their own .c file and have a ...
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14
votes
Accepted
Max-heap implementation in C
This is a max-heap datastructure,
and there is very consistent nomenclature here which reflects that.
I'm sure it is clear and commendable.
But I wouldn't have minded seeing it written in a comment, ...
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3
votes
Create a structure to store student data and display all the records in the array
General Observations
The code might be more readable if the indentation was 4 spaces rather than only 2 spaces. Many programmers use a tab for indentation. It is also common to have spaces between the ...
- 21.9k
8
votes
Create a structure to store student data and display all the records in the array
Undefined Behavior
s[i].name[50] = ' ';
This accesses outside of the array bounds.
fflush(stdin);
This is undefined behavior.
...
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2
votes
Follow Up: struct sockaddr storage initialization by network format-string
Improve naming uniformity
Instead of ....
netstring_internal.h
_INTERNAL_NETSTRING_H
netstr_error
NETSTR_PROTO
protocol_table
netstring_to_addrinfo.c
DOMAIN_BUFSIZ
...
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0
votes
Stack using doubly linked list
A stack should be a vector (that is, a dynamically-allocated array that remembers its size and capacity). Pop by decrementing the size. Push by reallocating if necessary and incrementing the size.
...
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1
vote
Array List C implementation
Give Your Structures More Informative Names
This is a dequeue, not a list. The Java class named ArrayList doesn’t have ...
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1
vote
Array List C implementation
A few more points:
In al_new you could use calloc to zero list->array and avoid the explicit loop to do so.
I think you ...
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1
vote
Stack using doubly linked list
Consider a uniform name space
Code such as this is not used in isolation, but with other code. The names chosen readily collide (like top) with existing code and ...
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4
votes
Accepted
Binary Search Tree implementation in C [1]
Fix compilation warnings
If your compiler isn't telling you about these, you haven't enabled enough warnings:
BST* create_bst(void) {
/*🔺🔺🔺*/
<...
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7
votes
Follow Up: struct sockaddr storage initialization by network format-string
Two minor points about this bit:
#if(_POSIX_C_SOURCE != 200112L)
#undef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 200112L
#endif
First, if you define ...
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7
votes
Follow Up: struct sockaddr storage initialization by network format-string
Declare only where needed:
//long port;
//port = strtol(*str, (char **) str, ...);
long port = strtol(*str, (char **) str, ...);
Simplify initialization:
...
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8
votes
Follow Up: struct sockaddr storage initialization by network format-string
There's a subtle mistake in this macro definition:
#define ARRAYSIZE(x) (sizeof(x) / sizeof(x[0]))
When we put parens around the expansions of macro arguments, ...
- 67.7k
9
votes
Accepted
Follow Up: struct sockaddr storage initialization by network format-string
Why not always use getaddrinfo()?
I kept the version with struct sockaddr_storage anyway
Why? It is inferior in every possible ...
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4
votes
Accepted
Command line calculator in C
Avoid global variables for this task
The key problem, in this case, is the added difficultly in proving code correctness.
Alternative:
In func(), instead of ...
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7
votes
Command line calculator in C
Don't write clever code:
if (printf("%g\n", b(&(const char *){*argv}, 0)) < 0)
You know you’re brilliant, but maybe you’d like to understand what ...
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7
votes
Command line calculator in C
General Observations
I'm going to address coding style here, since the code is almost unreadable.
If you are interested in getting your code reviewed you may want to pay attention to what the ...
- 21.9k
1
vote
7
votes
Accepted
Basic recursive descent parser in C
Portable?
"I wrote this code with portability in mind," --> Standard C lacks EINVAL.
longjmp(jmp, errno = EINVAL);
...
- 27.6k
3
votes
Recursive merge sort in C
This is a Great First Program in C
I don’t think I’ve seen a better one. However, I’ll suggest some improvements.
Write Contracts for your Functions
These can be short and sweet; names like ...
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4
votes
Accepted
Vectorized 16-bit addition in Standard C
You Have an XY-Problem
Let’s take a look at a very naïve loop to do this in C:
...
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3
votes
struct sockaddr_storage initialization by network format string
Candidate compare_until_delim() simplification
...
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