How to Find the Length of an Array

How do I find the length of an array?

If you mean a C-style array, then you can do something like:

int a[7];
std::cout << "Length of array = " << (sizeof(a)/sizeof(*a)) << std::endl;

This doesn't work on pointers (i.e. it won't work for either of the following):

int *p = new int[7];
std::cout << "Length of array = " << (sizeof(p)/sizeof(*p)) << std::endl;

or:

void func(int *p)
{
std::cout << "Length of array = " << (sizeof(p)/sizeof(*p)) << std::endl;
}

int a[7];
func(a);

In C++, if you want this kind of behavior, then you should be using a container class; probably std::vector.

How do I determine the size of my array in C?

Executive summary:

int a[17];
size_t n = sizeof(a)/sizeof(a[0]);

Full answer:

To determine the size of your array in bytes, you can use the sizeof
operator:

int a[17];
size_t n = sizeof(a);

On my computer, ints are 4 bytes long, so n is 68.

To determine the number of elements in the array, we can divide
the total size of the array by the size of the array element.
You could do this with the type, like this:

int a[17];
size_t n = sizeof(a) / sizeof(int);

and get the proper answer (68 / 4 = 17), but if the type of
a changed you would have a nasty bug if you forgot to change
the sizeof(int) as well.

So the preferred divisor is sizeof(a[0]) or the equivalent sizeof(*a), the size of the first element of the array.

int a[17];
size_t n = sizeof(a) / sizeof(a[0]);

Another advantage is that you can now easily parameterize
the array name in a macro and get:

#define NELEMS(x)  (sizeof(x) / sizeof((x)[0]))

int a[17];
size_t n = NELEMS(a);

How to get the length of an array inside an array?

How can I access the length of the Array contained inside jurusan?

It seems pretty straight to me:

var tif = ['idris','akbar','adyusman','a','g'];var te = ['tolaal','badri','alaina','b'];var mt = ['ressi','arian','tifa','c'];var jurusan= [tif,te,mt];// with forEach()jurusan.forEach(n => console.log(n.length));// with indexconsole.log(jurusan[0].length);console.log(jurusan[1].length);console.log(jurusan[2].length);

How to get length of an array in MySQL column?

you have two possibilities

  1. the old fashion ways
  2. Replace the ' with '
CREATE TABLE table1 (
`Id` INTEGER,
`Temp` VARCHAR(44)
);

INSERT INTO table1
(`Id`, `Temp`)
VALUES
('1', "['53682', '66890', '53925', '54847']"),
('2', "['53682', '66890', '53925', '54843','54890']");
seLECT `Id`, `Temp`, CHAR_LENGTH (`Temp`) - CHAR_LENGTH (REPLACE(`Temp`,',','')) + 1  as cnt FROM table1

Id | Temp | cnt
-: | :------------------------------------------- | --:
1 | ['53682', '66890', '53925', '54847'] | 4
2 | ['53682', '66890', '53925', '54843','54890'] | 5
CREATE TABLE table2 (
`Id` INTEGER,
`Temp` VARCHAR(44)
);

INSERT INTO table2
(`Id`, `Temp`)
VALUES
('1', '["53682", "66890", "53925", "54847"]'),
('2', '["53682", "66890", "53925", "54843","54890"]');
SELECT `Id`, `Temp`, JSON_LENGTH(`Temp`) AS cnt FROM table2

Id | Temp | cnt
-: | :------------------------------------------- | --:
1 | ["53682", "66890", "53925", "54847"] | 4
2 | ["53682", "66890", "53925", "54843","54890"] | 5

db<>fiddle here

How to find the length of an array in Google Sheets?

You could try COUNTA as this one returns the number of values in a dataset, instead of COUNT:

=COUNTA(SPLIT(E2,"/"))

Reference

  • COUNTA Function.

google sheet : How to find the length of array?

you can use ROWS or COLUMNS

=ROWS(QUERY(your_query))

Find the length of an array in Chapel

The correct answer is javascript:

var x = [1,2,3,4];
writeln(x.size);

For completeness, here is a summary of the built-in types with size-like fields:

  • range.size
  • domain.size
  • array.size
  • tuple.size
  • string.length

    • (string.size works as of Chapel 1.17 too)

How can I calculate the length of an array of objects with reduce?

Well the equivalent of data.length would be:

data.reduce(sum => sum + 1, 0);

But I don't see why you would do that unless you're trying to exclude blank values.

Array.size() vs Array.length

Array.size() is not a valid method

Always use the length property

There is a library or script adding the size method to the array prototype since this is not a native array method. This is commonly done to add support for a custom getter. An example of using this would be when you want to get the size in memory of an array (which is the only thing I can think of that would be useful for this name).

Underscore.js unfortunately defines a size method which actually returns the length of an object or array. Since unfortunately the length property of a function is defined as the number of named arguments the function declares they had to use an alternative and size was chosen (count would have been a better choice).

Finding length of array inside a function [duplicate]

There is no 'built-in' way to determine the length inside the function. However you pass arr, sizeof(arr) will always return the pointer size. So the best way is to pass the number of elements as a seperate argument. Alternatively you could have a special value like 0 or -1 that indicates the end (like it is \0 in strings, which are just char []).
But then of course the 'logical' array size was sizeof(arr)/sizeof(int) - 1



Related Topics



Leave a reply



Submit