Questions tagged [variable-length-array]
A variable length array (VLA) is an array in C99 and other languages whose size is non-constant.
variable-length-array
429
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Why VLA is comparable to gets?
It is well-known that MSVC doesn't, and won't support VLA feature.
During searching MSVC online reference, I found somewhat interesting sentence:
Variable length array (VLA) support isn't planned. ...
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-2
votes
2
answers
88
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How do I store integers into 2 different arrays in C programming
The first array is multiples of 5, second array is multiple of 9. I was able to store the input but the printed array seems wrong as it did not print my supposed numbers. Any kind soul could help and ...
-3
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0
answers
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i can't specify the size of my array using a variable in VS, but if I do it with other IDEs it works [duplicate]
This is the code in VS:
int main(){
int hi = 5;
int arr[hi]{};
}
The error:
Error(active) E0028 expression must have a constant value
The same code in code::Blocks:
int main() {
int ...
4
votes
1
answer
111
views
Check if array is a VLA at compile-time
@Lundin shows how to check if a passed expression is an array at compile-time here: Lvalue conversion of _Generic controlling expression involving array clang warning wrong?:
#define IS_ARRAY(T) ...
- 7,235
2
votes
3
answers
120
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How to assign anonymous VLA to pointer?
Currently I am assigning a VLA to a pointer as follows
struct Foo {
int* array;
};
int array[size];
struct Foo foo = {
.array = array;
};
Is it possible to replace this with an "...
- 35
6
votes
2
answers
115
views
What are the exact conditions under which type_name in sizeof(type_name) is evaluated? GCC evaluates f() in sizeof(int [(f(), 100)])
Context
The standard says (C17, 6.5.3.4 ¶2):
The sizeof operator yields the size (in bytes) of its operand, which may be an expression or the parenthesized name of a type. The size is determined from ...
- 1,808
2
votes
3
answers
242
views
Why is stack memory usage in C++ determined at compile time?
I first started going down this rabbithole after learning that VLAs (variable length arrays) are not compatible with C++. This is due to the fact that an array of variable length would not have a size ...
- 55
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2
answers
117
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What is the explanation of the odd behaviour in the size of the array in the given code? [duplicate]
#include<stdio.h>
int main(){
int n;
printf("Enter the number:");
scanf("%d",&n);
int array[n];
for (int i=0;i<=n;i++){
printf("%...
1
vote
1
answer
211
views
How do I construct an instance of a DST struct whose size is only known at runtime?
I have a struct that can be used in a fixed-size or unsized way, where the last element is an array of u8 items. We can write the following struct definition:
struct MyStructImpl<E: ?Sized> {
...
- 5,377
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1
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clarifications on assembler code when declaring an array with a size decided at runtime
I'm trying to understand how sizeof() works, so I made 2 arrays, and see what is assembled, I've not used -O3 option because I thought the code to be clearer and the code is not deleted by ...
- 1,563
2
votes
3
answers
421
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Return slice (or array of unknown size) from match expression
I'm trying to implement the following idea:
let command = ...;
let request = match subcommand {
Some(x) => [command, x as u8, (x >> 8) as u8],
None => [command],
};
request ...
- 21
0
votes
1
answer
233
views
Multiplot of variable length data using gnuplot
Here I have two data files with model parameters and RMSEs computed for them. I would like to get those RMSEs plotted for each model separately with the model also displayed on it.
Please help.
Data ...
- 15
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0
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36
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Using a variable in format string of Fortran and display the values side-by-side [duplicate]
I understood through this post on how to use a variable in format string.
write(*,'(1x,f10.5)')(j(i),i=1,nvar) seems to work but the values in 'j' are displayed row-wise. I want them to be displayed ...
- 15
30
votes
2
answers
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Linux memcpy restrict keyword syntax
I know that the restrict qualifier in C specifies that the memory region pointed by two pointers should not overlap. It was my understanding that the Linux (not SUS) prototype for memcpy looks like -
...
- 2,069
1
vote
3
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113
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Array using functions on C
A program to accept an array and diplay it on the console using functions.
Program should contain 3 functions including main() function.
Next two functions for accepting values to the array, and ...
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