A variable length array is an array in C99 and other languages whose size is unknown at compile time; instead, it's determined at runtime.
Questions tagged [variable-length-array]
413 questions
4
votes
1 answer
Variable Length Array with length 0?
In C, an array normally isn't allowed to have size 0 (unless I use the one or other compiler-side extension).
OTOH, there are VLAs whose length might turn out to be 0.
Are they allowed?
I am talking about the following code:
void send_stuff()
{
…
glglgl
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votes
4 answers
Which compiler should I trust?
This is going to be some what of a newbie question but I was trying to work on a small exercise in the C Language (not C++) and I was running into some issues.
Say I wanted to use an array within a method whose size depended on one of the…
Валера Горбунов
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4
votes
1 answer
Variable sized arrays in Objective-C?
Okay, so apparently this works:
void foo(size_t s) {
int myArray[s];
// ... use myArray...
}
Is this really legal? I mean, it must be, because it compiles (where the C compiler would reject it as non-constant). The first part of my…
i_am_jorf
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3
votes
3 answers
Taking sizeof of variable-length array — is there any benefit for doing so?
I am working on a piece of legacy code (no tests). I stumbled upon a section hidden inside several macros. It generates a warning if compiled with GCC's -Wvla.
The code in question is equivalent to what can be seen in this small program:
typedef…
Grigory Rechistov
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3
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1 answer
Does typedef (pointer to) VLA require evaluation of the size expression?
Does typedef VLA require evaluation of the size expression?
int f(void);
int main(void)
{
typedef int (T) [ f() ]; // is f required to be evaluated ?
T x;
return sizeof x;
}
Does typedef pointer to VLA require evaluation of the…
pmor
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3
votes
3 answers
Defining a C function that takes a 2D array with variables for dimension sizes
Edit: Turns out the compiler I'm using doesn't support variable length arrays so I have no way of achieving the notation I desire using MSVC
I have a function which takes in an array of strings and a query string, and returns the index of the…
eejakobowski
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3
votes
1 answer
How can I define a pointer to variable length array (VLA) in a struct (or equivalent)?
I declared many pointers to variable length array (VLA) in a function to allocate 2-D arrays dynamically; for example,
int M, N; // have some value
double (*arr1)[N] = calloc(M, sizeof(double [N]));
double (*arr2)[N] = calloc(M, sizeof(double…
Jeongu Kim
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3
votes
4 answers
Why is const int x = 5; not a constant expression in C?
I thought C had no more surprises for me, but this surprised me.
const int NUM_FOO = 5;
....
int foo[NUM_FOO];
==>error C2057: expected constant expression
My C++ experience has made me internally deprecate #define as much as…
pm100
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3
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1 answer
Vue on input value entered, move on to next field
I am new to Vue and it's my first project on Vue as well. I have three input fields which contains on empty values. Is there a way to move on to second input field automatically or make it select, if the input field 1 receives more than 5…
Yahoo
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3
votes
1 answer
Segfault after strsep only when compiling with clang 10
I am writing a parser (for NMEA sentences) which splits a string on commas using strsep. When compiled with clang (Apple LLVM version 10.0.1), the code segfaults when splitting a string which has an even number of tokens. When compiled with clang…
Samuel Dewan
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3
votes
3 answers
Array Mutation in C
If arrays in C are fixed in size, then how come this code is working properly?
This code works but my teacher said I did it in a wrong way...
int main()
{
int n,element,i;
printf("Enter the size of Array : ");
scanf("%d",&n);
int…
user11440137
3
votes
1 answer
sizeof operator in conjunction with variable-length array as function arguments
According to GNU's documentation on Arrays of Variable Length, one can use the sizeof operator for determining the size of a variable length array that was passed into a function:
You can also use variable-length arrays as arguments to…
dtracy
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3
votes
2 answers
Find the length of the array that was passed to you in Q#
I have an operation as follows to which the driver needs to send an array of qubits.
operation myOp(qubits: Qubit[]) : () {
// uses elements from the qubit array
}
How do I find the length of this array from within the code?
Mahathi Vempati
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3
votes
1 answer
Return a malloc’ed matrix while being able to use subscript notation
I have an exercise where I am supposed to use fixed-size arrays and in/out parameters to do stuff on matrices (add, scanf, print, etc.), but I’d like to do it on arbitrary-length matrices and return them rather than adding each time more (in/)out…
galex-713
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3
votes
3 answers
Initialize array size in C at File Scope
I'd like to initialize an array based on a calculation, but the compiler gives me an error when I try this (I'm using GCC version 6.3.0):
const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 600;
char…
dvanaria
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