The Urban Glass House. Penthouse of 7 HARRISON. The Urban Glass House. Create a Matrix class with a constructor or function that takes the row and column counts and creates the arrays (via new). Add a function which calculates the product and either saves the values or prints them out. If necessary add a function that prints out the results. Do this for a 2x2 matrix and see what is needed to scale up from there. Write A C Program To Multiply Any Two 3 X 3 Matrices. Write A C Program To Find Average Marks Of Three Subjects Of N Students In A Class By Using Array Of Structure. Write A C Program To Add And Subtract Two Matrices. Write A C Program Using Array Of Objects To Display Area Of Multiple Rectangles.
So we've talked about arrays before, however if we delve a little deeper, we can actually have arrays which have multiple dimensions! If you think of one array as a line of pieces of data, you could have an array of array which would essentially be a line of lines - so visually, a square of data. To take this a step further, you could have an array of arrays of arrays which would essentially give each point another line, thus visually creating the third dimension, making a cube of data. We could of course go on to the fourth, fifth, and sixth dimensions (and beyond!), however these can become a little difficult to visualize -- for reference, visualization as a line of cubes, square of cubes, and cube of cubes respectively will usually get you some reasonable comprehension of arrays up to 6D.
C Program to Perform Matrix Multiplication. CProgrammingServer Side Programming. A matrix is a rectangular array of numbers that is arranged in the form of rows and columns. An example of a matrix is as follows. A 3.2 matrix has 3 rows and 2 columns as shown below −. C: Multidimensional Arrays So we've talked about arrays before, however if we delve a little deeper, we can actually have arrays which have multiple dimensions! If you think of one array as a line of pieces of data, you could have an array of array which would essentially be a line of lines - so visually, a square of data.
Take a moment to just digest that dimension theory if you don't already understand it, and then think about how this could be useful. If you think about a simulation of a 2D world for example, you could store data for each point or block in the world in what is essentially a table cell - a piece of data in a 2D array. Similarly, some sort of 'real world' 3D simulation could store data for blocks, or chunks, or even particles in a 3D array (which would essentially have an 'x', 'y', and 'z' point if you are familiar with 3D co-ordinates).
Ok, we're done with theory for now - let's talk about to actually create multidimensional arrays. As I touched on earlier, a 2D array is actually just an array of arrays, and a 3D array is actually just an array of arrays of arrays. As such, instead of using one set of square brackets to create a basic 1D array, we could use two sets to create a basic 2D array, three sets to create a 3D array, and so on. A simple 2D array which essentially creates a 10×10 square 'table' which stores integers as each 'point' or 'cell' could be created as follows:
Values can then be modified and accessed in the array, much like in 1D arrays, by using the square brackets. So Table[0][1] would refer to the second ('1'st) element inside first ('0'th) element (remember that computers count from '0'). We can also initialize the values of an array by using curly brackets much like in single-dimensional arrays, however we must nest them to create the 'array in array' effect necessary for different dimensional arrays. In this example we might want something like the following:
Multidimensional arrays can also be easily initialized using loops, specifically (and most commonly), nested 'for' loops. Take, for example, the following code snippet in which 'i' loops through the rows and 'y' loops through the columns:
With a simple, clever cout addition - this data could be outputted to the user:
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With some further modifications to this, we could actually output the data in a table-like format. All we have to do is space-separate each column, and put a new line between rows:
Arrays, in C++, are simply arrangements of 'objects' -- in the basic usage we'll be using in this tutorial, we will be using arrays to simply store lists of data (of a certain because each piece of data stored (whether it be an integer, string, or something entirely different) has a number assigned to it that it can be referenced by. This is called the index, and the index number simply counts up from 0 as the array gets bigger - so the first element in the array would have the index of 0, the second the index of 1, etc.
Obviously storing data in this tabular-like manor is very useful in real world applications - a classic example that is usually given is pupils' scores in a test. Perhaps each student got a score out of 100 for their test - this data would be best stored in an integer array. In the real world the scores would probably be recorded in a text file or something similar, but we could always build in functionality to read this file and then store that data in an array inside our application.
Arrays can be created in C++ very much like 'normal variables' (with a) , followed by the index number of the element we wish to target in square brackets, followed by an equals sign and then the value we wish to set it to (and then obviously a semi-colon to end the line). So if we wanted to initialize the first element (of index 0) in our array to the value '15', we could write the following:
The same could also be done for the scores of the other members of the class (elements of the array from index 0 to index 29). If we then wanted to use these values later (for example if we wanted to cout one or all of the elements), we can access a certain element of the array just as we did when we were assigning values to each element - by writing the array name and then the index number in square brackets. So we could output the first element in the array (remember, this is the one with the index of 0!) by writing something like cout << ClassScores[0];.
You may have noticed when we learnt how to initialize the elements in arrays earlier, that the process was extremely long and drawn out (imagine having to initialize hundreds of array elements!) - luckily there is an easier way to initialize the elements in an array. Instead of individually setting each element to a certain value (which can be done at any point in the program, not just at element initialization) we can actually initialize the elements when we declare the array! This method of initialization is accomplished by simply shoving an equals sign after the declaration of the array and then specifying the different array elements, with commas separating them, in curly brackets. This method doesn't require any value in the square brackets either as the compiler can calculate how many elements we are initializing and set the array size to that! To show this method of initialization, let's just set some values for each score in the class at the array declaration - let's cut it down to 20 this time for the sake of simplicity:
With an array declared and initialized, we can do a whole bunch of stuff with it! A nice example might be outputting all of the students' scores - unfortunately, however, there's no really easy and clean way to do this without knowing about 'loops' or some other fancy things, so for now we'll have to just repeat a bunch of code. Generally speaking when you feel your repeating a lot of code when C++ programming, there is probably a better way to accomplish what you're trying to do, but for now just go with it. I've cut the array down to 5 elements this time, simply because I don't want to have to copy and paste a single line 20 times - you'll learn about a more elegant solution to our problem of outputting array elements in the next tutorial.
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Another really cool thing that you could do with arrays is trying to 're-create' the 'string', character arrays like 'H', 'e', 'l', 'l', 'o' were used -- character arrays of this kind can, unlike most, actually be outputted just by couting their name because they're so much like strings. It's worth nothing that when creating character arrays like these, however, you should also add another character onto the array, which is a 'null character' which shows where the string ends - this is called the null termination of a string, and the null character is expressed via '0'.
'Real' strings can actually be treated just like character arrays in some circumstances too - using square brackets and an index number gets a certain character of the string (for example string_name[1] of 'Hello' would be 'e'). If you're feeling up to the challenge, try moving a string variable defined in code (of a fixed length) like string one = 'Hello';, to a 'char' array of the same length using the information above. It probably seems a bit pointless, I know, but it's good practice with using arrays. If you don't feel up to the challenge, the code for doing such a thing (which once again would be a bit cleaner with 'loops'), is as follows:
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