How do you use .length to get the number of rows in a 2D array?

How do you use .length to get the number of rows in a 2D array?

We use arrayname. length to determine the number of rows in a 2D array because the length of a 2D array is equal to the number of rows it has. The number of columns may vary row to row, which is why the number of rows is used as the length of the 2D array.

Can we create a 2D array with different row size?

Arrays of arrays of different size is possible in C. Simply they are not 2D arrays but arrays or pointers.

How do you add to a 2D array?

For inserting data In 2d arrays, we need two for loops because we are working with rows and columns here.

1. Ask for an element position to insert the element in an array.
2. Ask for value to insert.
3. Insert the value.
4. Increase the array counter.

How do you access a row in a 2D array?

An element in 2-dimensional array is accessed by using the subscripts. That is, row index and column index of the array. int x = a[1,1]; Console.

How can you increase size of dynamically allocated array?

4 Answers

1. Allocate a new[] array and store it in a temporary pointer.
2. Copy over the previous values that you want to keep.
3. Delete[] the old array.
4. Change the member variables, ptr and size to point to the new array and hold the new size.

Can I increase the size of dynamically allocated array *?

Simple answer is no, this cannot be done. Hence the name “static”. Now, lots of languages have things that look like statically allocated arrays but are actually statically allocated references to a dynamically allocated array. Those you could resize.

Can you change the size of allocated arrays?

Size of an array If you create an array by initializing its values directly, the size will be the number of elements in it. Thus the size of the array is determined at the time of its creation or, initialization once it is done you cannot change the size of the array.

Why can’t I simulate a 2D array?

The more major problem is that you’ve misunderstood the memory allocation that’s needed to simulate a 2D-array. Your scanf () call is incorrect; you are not passing pointers to it. You actually need the pointer stored in numbers, the array of pointers, and the array of double.

What does realloc do to pointers?

Good luck. On success, realloc frees the pointer you pass to it and returns a pointer to the newly allocated memory. You’re getting “junk values” because dereferencing a pointer to freed memory is undefined behavior. It’s not pretty, but the way to fix this (as another answer pointed out) is to pass a triple pointer ( int*** ).

What happens if realloc() fails to work?

And don’t overwrite the realloc () ed pointer before checking if the allocation was succesfull, because if it fails you wont be able to free the previous pointer because you would have lost reference to it, causing a memory leak.