Split Array into Two Arrays by Index Even or Odd

How to split an array into two arrays, one for even and one for odd in C

Un-initialized variables can contain anything, it is better to start of by initializing.

This

int array100[100];
int arraypar[100];
int arrayimpar[100];

Should be:

int array100[100] = {0};
int arraypar[100] {0};
int arrayimpar[100] = {0};

And since C uses 0 base array indexing, you are probably seeing a run time error; Dereference of out-of-bounds pointer (or similar) if the code shown in your post is the actual code you are using.

This:

for(i=1;i<=100;i++){
      ^  ^^
    printf("%i ", arraypar[i]);
}

Should be this:

for(i=0;i<100;i++){
      ^  ^
    printf("%i ", arraypar[i]);
}

Same for the next for loop.

Also, a suggestion to help you troubleshoot. I would start off by initializing array100 with a known set of sequential values to easily test whether the values are being split properly:

int array100[100] = {1,2,6,4,5,6,7,8,9,10,
                     11,12,16,14,15,16,17,18,19,
                     20,21,22,26,24,25,26,27,28,29,
                     60,61,62,66,64,65,66,67,68,69,
                     40,41,42,46,44,45,46,47,48,49,
                     50,51,52,55,54,55,56,57,58,59,
                     60,61,62,66,64,65,66,67,68,69,
                     70,71,72,77,74,75,77,77,78,79,
                     80,81,82,88,84,85,88,87,88,89,
                     90,91,92,99,94,95,99,97,98,99,100};

Now run your program with the rand() section commented out to see what you get. If there are problems, they will be easier to see then looking at a collection of randomly generated numbers.

Divide array into two arrays and set values to odd and even

You need to check the value, not the index.

if (arrayMain[i] % 2 == 0) {
//  ^^^^^^^^^^ ^

Split array into two arrays by index even or odd

One solution, using anonymous functions and array_walk:

$odd = array();
$even = array();
$both = array(&$even, &$odd);
array_walk($array, function($v, $k) use ($both) { $both[$k % 2][] = $v; });

This separates the items in just one pass over the array, but it's a bit on the "cleverish" side. It's not really any better than the classic, more verbose

$odd = array();
$even = array();
foreach ($array as $k => $v) {
    if ($k % 2 == 0) {
        $even[] = $v;
    }
    else {
        $odd[] = $v;
    }
}

split an array into two arrays based on odd/even position

You could try:

var Arr1 = [1,1,2,2,3,8,4,6],
    Arr2 = [],
    Arr3 = [];

for (var i=0;i<Arr1.length;i++){
    if ((i+2)%2==0) {
        Arr3.push(Arr1[i]);
    }
    else {
        Arr2.push(Arr1[i]);
    }
}

console.log(Arr2);

JS Fiddle demo.

How to split an Array into Odd Array and Even Array

You've to use charCodeAt method because allData is an array of string not array of numbers.

It's the solution of your problem:

if ( ( allData[i].charCodeAt(0) % 2 ) === 0) { your code }

=================

as Thomas Scheffer mentioned it seems u want to sort based on character index not its value .

so if u want to sort based on index u have to write :

if ( ( i % 2 ) === 0) { your code }

it converts like this :

allData = ["b","f","z","w"] => { odd=["f","w"], even=["b","z"]  }

but if u want to sort based on character value u have to write :

if ( ( allData[i].charCodeAt(0) % 2 ) === 0) { your code }

it converts like this :

allData = ["b","f","z","w"] => { odd=["w"] , even=["b","f","z"] }

Divide/Split an array into two arrays one with even numbers and other with odd numbers

Your error is in if condition, you want to check if the number is odd or even, you have to use modulus % operator. So your code becomes like this

<?php $array = array(1,2,3,4,5,6);
$length = count($array);
$even = array();
for($i=0; $i < $length; $i++){
  if($array[$i]%2 == 0){
$even[] = $array[$i];
}
else{
  $odd[] = $array[$i];
}
}
print_r($even);
echo "<br/>";
print_r($odd);

Objective-C Split an array into two separate arrays based on even/odd indexes

There are following ways you can achieve that:-

The first and second one solution are already mentioned by the above two. Below are the implementation of the same:-

//First Solution
NSArray *ar=@[@"1",@"2",@"3",@"4",@"5"];
NSMutableArray *mut1=[NSMutableArray array];
NSMutableArray *mut2=[NSMutableArray array];
[ar enumerateObjectsUsingBlock:^(id object, NSUInteger idx, BOOL *stop) {
    if (idx%2==0)
    {
        [mut1 addObject:object];
    }
    else
    {
        [mut2 addObject:object];
    }
}];

//Second Solution
NSMutableIndexSet *idx1 = [NSMutableIndexSet indexSet];
NSMutableIndexSet *idx2 = [NSMutableIndexSet indexSet];
for (NSUInteger index=0; index <ar.count(); index++)
{
   if(index%2==0)
    {
        [idx1 addIndex:index];
    }
    else{
        [idx2 addIndex:index];
    }
}
NSArray *evenArr=[ar objectsAtIndexes:idx1];
NSArray *oddArr=[ar objectsAtIndexes:idx2];
NSLog(@"%@",evenArr);
NSLog(@"%@",oddArr);

C Array Split By Odd Even Indexes Gives Garbage Values

Any access to a[i] or b[i] will be out of bounds when i is greater than 2. You should be using the aa and bb indices when filling the a[] and b[] arrays.

Also, the test for even or odd indices can be simplified since 0 is even.

Here is the fixed version of the array splitting loop:

    for (i = 0; i < n; i++)
    {
        if (i % 2 == 0)
        {
            // even
            a[aa] = arr[i];

            // For debug purpose
            printf("a[%d]=%d, arr[%d]=%d, aa=%d\n", aa, a[aa], i, arr[i], aa);

            aa++;
        }
        else
        {
            // odd
            b[bb] = arr[i];

            // For debug purpose
            printf("b[%d]=%d, arr[%d]=%d, bb=%d\n", bb, b[bb], i, arr[i], bb);

            bb++;
        }
    }