Q: I can't understand what happen with the array of learn? I think it should print ``` Array after sorting: [10, 23, 25, 32] ``` but it not? ``` var insert = function(array, rightIndex, value) { for(var j = rightIndex; j >= 0 && array[j] > value; j--) { array[j + 1] = array[j]; } array[j + 1] = value; }; var insertionSort = function(array) { for (var i = 1; i < array.length; i++) { insert(array, i-1, this.array[i]); } }; var array = [22, 11, 99, 88, 9, 7, 42]; insertionSort(array); println("Array after sorting: " + array); Program.assertEqual(array, [7, 9, 11, 22, 42, 88, 99]); var learn = [10, 23, 32, 25]; insertionSort(learn); //println(learn); println("Array after sorting: " + learn); Program.assertEqual(learn, [10, 23, 25, 32]); ```

You shouldn't need to use `this` When you use `this.array` it is referring to the `var array` declared outside of the function, instead of the local var `array` that was passed in as a parameter the function. Remove the `this` and things should work better.

Q: what is the wrong with below code ?? [Edited to include only relevant code] ``` var array = [78, 34, 99, 88, 29, 7, 42]; insertionSort(array); println("Array after sorting: " + array); Program.assertEqual(array, [7, 29, 34, 42, 78, 88, 99]); ```

The code is fine, but you have changed the original array and assert, which is confusing the grader The original array is: `var array = [22, 11, 99, 88, 9, 7, 42];` The original assert is: `Program.assertEqual(array, [7, 9, 11, 22, 42, 88, 99]);` Change those two lines back to the original and it should work ok

Q: I have written this code and the error message is showing that a function is taking to log to run and it is pointing to the insert function which is pre-written var insert = function(array, rightIndex, value) { for(var j = rightIndex; j >= 0 && array[j] > value; j--) { array[j + 1] = array[j]; } array[j + 1] = value; }; var insertionSort = function(array) { for( var i=1; i<array.length ; i++) { insert(array,i,array[i]); } }; var array = [22, 11, 99, 88, 9, 7, 42]; insertionSort(array); println("Array after sorting: " + array); //Program.assertEqual(array, [7, 9, 11, 22, 42, 88, 99]);

This might be because in the loop, the condition is i < array.length. However, while running the code, array length increases because of the insert function. So, the loop cannot end.

Question 1

Why do you we have to use "var someFunc = function() {}" rather than "function someFunc() {}" ? The differences between the two are minor and I prefer the latter syntax when possible.

Accepted Answer

The code inside the code window is working within an environment.
-variables and object which appear to be global within the environment aren't really global in scope, they are just at the scope level that the environment is at
- I suspect that, you can't use `function foo(){}` because this would make the function truly global
 i.e. it would be at the level of the window object, which could cause all kinds of problems 
- I suspect, the same rationale applies to why variables must be declared using `var` instead of them automatically being created as globals

So, I believe that the syntax is restricted, because you're stuck in the Matrix, and allowing you to use the restricted syntax would cause the illusion to be shattered.

Hope this makes sense

Question 2

in the inset function var insert = function(array, rightIndex, value) {
    for(var j = rightIndex;
        j >= 0 && array[j] > value;
        j--) {
        array[j + 1] = array[j];
    }   
    array[j + 1] = value; 
};

can someone explain to me array[j + 1] = value; this line?
I know array[j + 1] = array[j]; this is sliding all bigger element than the value to its right but should not the small value be inserted at array[j] position? why array[j+1] position??

Accepted Answer

if you exited the loop you have just failed the check for `j >= 0 && array[j] > value`.

There are two cases where this would happen:
1)  j is -1, (to the left of the array), in which case value is the smallest element, which you want to be inserted at index 0. 
Note that:  j + 1 = -1 + 1 = 0

2) j is the index of the largest element that is smaller than value. In which case you want to insert value immediately after it i.e. j+1

Question 3

I can't understand what happen with the array of learn?
I think it should print 
```
Array after sorting:   [10, 23, 25, 32]
```
but it not?
```
var insert = function(array, rightIndex, value) {
    for(var j = rightIndex;
        j >= 0 && array[j] > value;
        j--) {
        array[j + 1] = array[j];
    }   
    array[j + 1] = value; 
};

var insertionSort = function(array) {
    for (var i = 1; i < array.length; i++) {
        insert(array, i-1, this.array[i]);
    }
};

var array = [22, 11, 99, 88, 9, 7, 42];
insertionSort(array);
println("Array after sorting:  " + array);
Program.assertEqual(array, [7, 9, 11, 22, 42, 88, 99]);

var learn = [10, 23, 32, 25];
insertionSort(learn);
//println(learn);
println("Array after sorting:  " + learn);
Program.assertEqual(learn, [10, 23, 25, 32]);

```

Accepted Answer

You shouldn't need to use `this`
When you use `this.array` it is referring to the `var array` declared outside of the function, instead of the local var `array` that was passed in as a parameter the function. Remove the `this` and things should work better.

Question 4

what is the wrong with below code ??

[Edited to include only relevant code]
```
var array = [78, 34, 99, 88, 29, 7, 42];
insertionSort(array);
println("Array after sorting:  " + array);
Program.assertEqual(array, [7, 29, 34, 42, 78, 88, 99]);
```

Accepted Answer

The code is fine, but you have changed the original array and assert, which is confusing the grader

The original array is:  `var array = [22, 11, 99, 88, 9, 7, 42];`
The original assert is: `Program.assertEqual(array, [7, 9, 11, 22, 42, 88, 99]);`

Change those two lines back to the original and it should work ok

Question 5

I have written this code and the error message is showing that a function is taking to log to run and it is pointing to the insert function which is pre-written

var insert = function(array, rightIndex, value) {
    for(var j = rightIndex;
        j >= 0 && array[j] > value;
        j--) {
        array[j + 1] = array[j];
    }   
    array[j + 1] = value; 
};

var insertionSort = function(array) {
for( var i=1; i<array.length ; i++)
{
    insert(array,i,array[i]);  }
};

var array = [22, 11, 99, 88, 9, 7, 42];
insertionSort(array);
println("Array after sorting:  " + array);
//Program.assertEqual(array, [7, 9, 11, 22, 42, 88, 99]);

Accepted Answer

This might be because in the loop, the condition is i < array.length. However, while running the code, array length increases because of the insert function. So, the loop cannot end.

Computer science

Course: Computer science > Unit 1

Insertion sort pseudocode

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