All Questions
24 questions
0
votes
1
answer
186
views
Elegant way in C to store many parameters with default value and current value in embedded flash
I'm programming an embedded system that has a number of user configurable parameters, which are stored in flash memory. I have to store a default value for each parameter as well as the user settings. ...
- 175
26
votes
6
answers
24k
views
How can Rust be "safer" and "faster" than C++ at the same time?
I have been told that Rust is both safer and faster than C++. If that is true, how can that be even possible? I mean, a safer language means that more code is written inside the compiler, right? More ...
- 393
5
votes
2
answers
3k
views
Why does C not support direct array assignment?
In C you cannot assign arrays directly.
int array[4] = {1, 2, 3, 4};
int array_prime[4] = array; // Error
At first I thought this might because the C facilities were supposed to be implementable with ...
- 1,199
-2
votes
1
answer
120
views
Are jagged arrays lvalue or not?
When I was study lvalue i see that
C expression can be lvalue if a subscript ([]) expression that does not evaluate to an array.
(from
https://docs.microsoft.com/en-us/cpp/c-language/l-value-and-r-...
- 113
2
votes
2
answers
706
views
sizeof(a)/sizeof(a[0]) vs sizeof(a)/sizeof(t) where t is type in C from K.N.King
I'm trying to understand why sizeof(a)/sizeof(t) is inferior for getting the length of an array to sizeof(a)/sizeof(a[0]) if just as it's possible to have different types, my elements could also be of ...
- 41
1
vote
3
answers
2k
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 this ...
user340139
2
votes
3
answers
3k
views
Return array pointers vs. populating an array inserted as a parameter?
Which is better? I noticed the latter is used in a lot of C code. People will typically malloc an array, and then pass that as a parameter to a function, which will then populate it. Whereas in Java, ...
- 149
2
votes
1
answer
201
views
Handling out of bounds requests in embedded C library
We're currently building a library in C that configures itself from tables in EEPROM.
This leaves the possibility however that some caller requests a field that is out of bounds, and the question ...
- 39
1
vote
2
answers
569
views
How do I best store a value with multiple keys?
I need to store two 32-bit numbers in a way that is quickly accessible and as storage space efficient as possible. My keys are a combination of the following two
values:
port: 0 - 29
vlan: 1 - 4095
...
- 139
0
votes
4
answers
2k
views
How does C know the bounds of a multi-dimensional array?
Coming from Python, if C does not have array bounds, how does it know where a[1] starts?
int a[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
b = a[1][1];
- 121
-1
votes
1
answer
5k
views
(Multidimensional array in C) How to make my output in a vertical position rather than in horizontal when the size of the array is n[3][4] [closed]
I would like to have some help.
I must find a way that the output must be:
A B C
90 60 80
50 100 70
100 20 100
10 50 75
Because the previous output is:
A 90 50 100 10
B 60 100 ...
15
votes
1
answer
833
views
Why prefer sizeof(element) over sizeof(TYPE) for calculating the number of elements in an array?
I'm reading "King K.N's C programming" and found the following statement:
We discussed using the expression sizeof(a)/sizeof(a[0]) to calculate the number of elements in an array. The expression ...
- 169
-3
votes
1
answer
86
views
How can this allocation of bi-dimensional arrays work? [closed]
I was seeing this post on StackOverflow and saw a new way (at least for me) to define a two dimensional array of 5x5, it works well, but I feel I don't understand what is going on in the background.
...
- 729
1
vote
3
answers
665
views
Question about multidimensional arrays
I was wondering something about the multidimensional arrays and then I got a doubt about a concept, specifically about their representation on memory.
For example, an array can be defined as follows.
...
- 729
14
votes
6
answers
9k
views
Why can't C arrays have 0 length?
The C11 standard says the arrays, both sized and variable length "shall have a value greater than zero." What is the justification for not allowing a length of 0?
Especially for variable length ...
- 251