126 questions
1
vote
2
answers
173
views
Create enum values in array initializer in C++
I have a small table of structs, that I would like to refer in code by a short name. However, using a string as name would mean to have some lookup search every time this table needs to be accessed. ...
- 11.4k
-2
votes
1
answer
164
views
Compilation-time initialization of an array of struct with the information of another array
Let Foo be a structure holding an integer.
Now, I need to initialize at compilation time an array of Foo from the values coming from an array of integers.
Of course, one can hand-write it but having a ...
- 4,315
0
votes
1
answer
125
views
Why these 2 codes don't give similar output?
The difference is in 4th line for both code(given below).
In 1st one, I declared some variable and then initialized the array.
In 2nd one, I initialized the array first and then declared the variables....
- 29
0
votes
0
answers
72
views
What's the difference between an 'empty' list (ar[5]={} )and 'no-list-at-all' (ar[5]) in array initialisation in C++? [duplicate]
I'm just a beginner in C++. In my textbook it is stated that, "if the number of initial values is less than the size of the array, they will be stored in the elements starting from the first ...
0
votes
2
answers
214
views
Initialize the size of global array
I need to put the output of arr in global array because I need to use the array in main function. How can I initialize the array in global and I don't know the size of it ? any idea please?
globarr[]; ...
- 727
0
votes
3
answers
850
views
Why does a loop or list comprehension work to initialize an array, but individually initializing the elements does not?
Why does initializing the array arr work when it is done as a list comprehension (I think that is what the following example is --not sure), but not when each array location is initialized ...
- 248
55
votes
4
answers
13k
views
Are char arrays guaranteed to be null terminated?
#include <stdio.h>
int main() {
char a = 5;
char b[2] = "hi"; // No explicit room for `\0`.
char c = 6;
return 0;
}
Whenever we write a string, enclosed in double ...
- 3,068
0
votes
1
answer
121
views
Don't understand "Extra argument 'repeatedValue' in call"
What could be wrong with:
let myArray = [UInt](count: 256, repeatedValue: 0)
that leads to the error Extra argument 'repeatedValue' in call?
I found this in existing code I'm adding to my Swift 5 app....
- 23.1k
0
votes
1
answer
116
views
How do we take any array value without initialization in vb.net?
Like with initialization:
We take like:
Dim a() as integer = {1,2,4,6}
And if i want to print the array list it will be 1 , 2 ,4,6 as output
But how can i take any value i.e n value to print n ...
0
votes
0
answers
51
views
Modifying 2D array elements
Basically I'm trying to modify an element in a 2D array. How the array is initialized seems to be effecting the behaviour. I'm new to Ruby so I'm not sure how initializing an array would effect this. ...
2
votes
1
answer
101
views
Does array initialization with a string literal cause two memory storage? [duplicate]
int main()
{
char a[] = "123454321";
}
"123454321" is a string literal and a string literal sets aside memory storage. a is defined by the statement which also causes memory ...
- 777
0
votes
2
answers
57
views
Problem with initializing an array of List<int> with Initialize method
I want to implement a graph with an array of List<int>, but when I try to initialize the entries with Array.Initialize() with the default values (by calling a parameterless constructor of List&...
0
votes
2
answers
157
views
Is arr[i] = i; legal?
I want to initialize a value of all array members to their index.
int main()
{
int i;
int arr[10];
for (i = 0; i <= 9; i++)
arr[i] = i;
}
Should I consider the sequence point ...
- 777
2
votes
2
answers
2k
views
how to initialize a matrix in C
I need to initialize a h x h matrix in C with spaces.
How to properly do it without cycles?
int h = 8;
char arr[h][h] = {{' '}}; // does not work....
- 15.4k
0
votes
2
answers
107
views
Pointer Arrays and Functions CPP
I wonder If there's a way to assign a dynamic array (C style), values like in the case of a non dynamic array (instead of matrix[0][0] = ...), e.g.:
int n = 3;
int ** matrix = new int*[n];
for(int i =...
- 304
2
votes
3
answers
3k
views
Why do we need a null terminator in C++ strings?
I'm new to programming and very new to C++, and I recently came across strings.
Why do we need a null terminator at the end of a character list?
I've read answers like since we might not use all the ...
- 347
2
votes
2
answers
69
views
Where do the Array gets initialized if we do not pass the size of the array explicitly?
I am new to programming. While learning the data structure Array, I came to know that we have to initialize the array with the size, while creating one. But I also saw a code snippet in one of the ...
- 79
0
votes
0
answers
45
views
Specifying specific values in an array initialization
I recall that in C# a notation similar to the one below would be a correct array initializer.
int[] array = new int[3]
{
[1] = 5;
};
This should initialize the array with all values as default (0 ...
- 334
0
votes
2
answers
332
views
How to initialise multiple array in single line in Ruby?
I'm trying to do some calculations and get the groups and departments array from there.
but if I'm returning it like this [], [] It is giving error, while if I return it like [[],[]]
it is working ...
- 45
4
votes
3
answers
163
views
Constructor ambiguity with array initializer
I have an issue in that I cannot use a certain constructor with an array initializer when using VS2017 (C++14, C++17 and ISO latest).
I get an C2397 conversion from 'double' to 'unsigned int' ...
- 1,047
1
vote
1
answer
87
views
Why does this bit of C# code with array initializer not refactor how I expect
I have the following code;
char[] leadingDot = { '.' };
string trimStart = fileName.TrimStart(leadingDot);
I cannot seem to figure out the syntax to combine it into a single line. ReSharper has no ...
- 2,056
4
votes
2
answers
297
views
Kotlin array <init>ialization [duplicate]
I will be reading data from a byte stream. Are the indices given by Kotlin to an array generation function (as described in https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-array/-init-.html) ...
- 9,953
1
vote
1
answer
3k
views
C++ initialize/fill static member std::array elements to specific value
I'm wondering if there is a proper way to do this.
Given the example:
struct Test {
static std::array<unsigned, 123> data;
};
std::array<unsigned, 123> Test::data = {};
If I want to ...
- 763
4
votes
2
answers
560
views
Why {0} assignation works but not {5} for an array [duplicate]
I tried the following code:
int a[4] = {0};
int b[4] = {5};
int c[4];
printf("%d %d %d %d %d %d\n", a[0], a[3] , b[0], b[3], c[0], c[3]);
And got the following result:
0 0 5 0 random random
While I ...
- 1,351
1
vote
3
answers
510
views
Why does std::strlen() work on char arrays WITHOUT terminating null characters? Is this a compiler optimization?
All of the reading I've done says that passing a non null-terminated char array to std::strlen is undefined behavior and will likely cause the program to crash. However, the code below (compiled with ...
- 63
4
votes
1
answer
495
views
Different assembly when initializing an array with a string literal
According to this thread, initializing an array with a shorter string literal pads the array with zeros.
So, is there any reason why these two functions (test1 and test2) would produce different ...
- 4,514
3
votes
2
answers
4k
views
ARM assembly memcpy equivalent
I am viewing the assembly output of this function:
extern void write(char * buff);
void test(int x)
{
// copy "EXAMPLE\0\0\0\0\0..."
char buff[16] = "EXAMPLE";
// set ...
- 4,514
3
votes
2
answers
141
views
gcc compiler report warning but a.out works smoothly otherwise
I am following the book "C Primer Plus" and encounter such a snippet of code:
// designate.c -- use designated initializers
#include <stdio.h>
#define MONTHS 12
int main(void)
{
int days[...
- 22.7k
9
votes
1
answer
703
views
Is it allowed to initialize array recursively? [duplicate]
I have the following code snippet:
int i[] = {42, i[0]};
Is such initialization allowed or leads to undefined behaviour?
Three major compilers (gcc, clang, msvc) give me 42 for i[1]. Hence looks ...
- 5,182
1
vote
1
answer
1k
views
Assign array's values at compile time with and enum as index (C++)
I'm trying to use a C-style array as a map through enums but I can't initialize arrays by parts... I'll explain myself better through code:
I have something like:
enum Objects{CAR = 0, PLANE, BOY};
...
- 75
1
vote
0
answers
49
views
Prevent specifying each integral value as unsigned in array-initializer
Consider the following function which takes a reference to an array of a size N deduced at compile time:
template <size_t N>
void array_consumer(unsigned const (&source)[N]) {
// ...
}
I ...
- 66.3k
1
vote
0
answers
62
views
Using previous element's value in an array's initialization [duplicate]
So I've found this code works:
int foo[] = {0, foo[0] + 1, foo[1] + 2, foo[2] + 4 };
Is this officially legal? I thought that I was making an initializer_list here, but if I can access previously ...
- 39.1k
-2
votes
3
answers
4k
views
Declare an array of queues [duplicate]
What is the language grammatical problem in my code?
I want to declare an array of queues. Is this the right way to declare and use them?
public static void Main(string[] args)
{
...
- 43
2
votes
3
answers
469
views
How to initialize only a slice of a character array?
I am aware of C's (pretty neat) array initialization syntax, like
char arr[12] = {[0] = '\n', [4] = 'z'};
to initialize some specific members in the array, but is there a means to initialize a whole ...
- 602
6
votes
2
answers
214
views
Is there a difference between these ways of initialising a C array in C++?
I want to initialise all members of the array to zero, or nullptr
struct Window{ int a;};
int main()
{
Window* list[4] = { 0, 0, 0, 0 };
Window* list2[4] = {0};
Window* list3[4] = {};
...
- 16.3k
2
votes
3
answers
1k
views
C - Creating an initialisation macro for an array of structs
I would like to do this with a macro:
typedef struct _TIMER_llist {
struct _TIMER_llist *next;
uint32_t time;
const int id;
} TIMER_llist;
TIMER_llist _timer_llists[] =
{
{ .id = 1, ....
- 143
0
votes
1
answer
449
views
How to parse dynamic array arguments to a variable in excel vba
※ This question is a continuation of below problem
How to use nested loop for a Matrix cell in excel vba
I would like to pass dynamic Array(arguments), and i was trying below, but it is not working ...
- 15
0
votes
2
answers
834
views
Adding elements of multiple arrays into a new array in C
I am trying to add some polynomials after multiplying each by a different constant. I have been able to setup the arrays and multiply by the constants, but when I get to the addition of each position ...
1
vote
4
answers
1k
views
Static Bool Array Not initializing as set
Why are my array of static bools not initialized properly? Only the first one is initialized - I suspect this is because the array is static.
The following MWE was compiled with GCC and is based on a ...
- 93
0
votes
1
answer
3k
views
C# reset an array to its initialized values?
Lets say I have an array of employee wages in the order of average, max, and min:
int[] wages = {0, 0, Int32.MaxValue};
The above code is initalized so that as Im finding the max I can do a ...
- 1,251
3
votes
3
answers
2k
views
C# - Can I use an array initializer to build one byte array out of another?
I'd like to use an array initializer to build one byte array out of another byte array as well as some other bytes that form a header/trailer. Basically, I'd like to do something like this:
byte[] ...
- 1,731
-1
votes
1
answer
1k
views
How do I initialize multidimensional array in C? [duplicate]
I want to initialize multidimensional array in C.
I use usually the code below.
#include <stdio.h>
int main()
{
int a[10][10] = {{0}, {0}};
return 0;
}
Is my code right, and is there ...
20
votes
2
answers
942
views
What language standards allow ignoring null terminators on fixed size arrays?
We are transitioning C code into C++.
I noticed that the following code is well defined in C,
int main(){
//length is valid. '\0' is ignored
char str[3]="abc";
}
as it is stated in Array ...
- 38.3k
1
vote
4
answers
1k
views
Initializing a Table
So this is my program so far:
#include <iostream>
#include <windows.h>
using namespace std;
int colonne;
int ligne;
void initDamier (int damier[ligne][colonne])
{
for (int i = 0; i &...
- 77
-3
votes
1
answer
1k
views
set the char array to all zero values (in C)
How can I set the vars array to all zero '0' values?
typedef char array_t[100];
void
setvars(array_t vars[], int lens[]) {
/*vars : 10 numbers
lens : the length of 10 numbers in vars
*/
.
.
.
}
...
- 1
0
votes
1
answer
220
views
Confusion with multidimensional array initialization in C#
I'm a programming newbie and I just started learning about arrays.
What confuses me is the way one can initialize a multidimensional array in C#. And that is because I don't specify the coordinates of ...
user6104944
0
votes
2
answers
108
views
Position of each element of an array initializer
So I want to get the position of each of the element within the array initialiser for example:
int [][][] testArray = new int [][][] {{{1,2},{3,4}},{{5,6},{7,8}}};
how would i be able to get the ...
- 13
2
votes
1
answer
599
views
Failed to deduce bounds from initializer for multi-dimensional arrays
This following code does not compile:
int main() {
int a[][] = { { 0, 1 },
{ 2, 3 } };
}
The error message produced is
error: declaration of 'a' as multidimensional array must have ...
- 15.1k
-1
votes
2
answers
72
views
No enclosing instance is in scope with double brace initializers
I have some classes nested one in another
public abstract class I
{
public abstract int f();
}
public class J
{
private List<I> li;
public J(List<I> l)
{
li = l;
...
- 1,059
0
votes
0
answers
37
views
Initialize array of derived objects like aggregate [duplicate]
Consider the following hierarchy of classes:
struct B {
int i;
};
struct D : B {
int j;
};
B is aggregate class, but D is not (because of base class existance).
Is there a way to initialize ...
- 5,182