I am quite confused in array loops that do have nested ones to print the Two Dimensional array. /it contains a loop without curly braces and second one has just opposite way of representing the braces for loops ...
Since i am learning I have just typed the code and got output.
public class TwoDimensional {
private int i, j, k = 0;
int[][] twod = new int[4][5];
public void DoubleT() {
for (i = 0; i < 4; i++)
for (j = 0; j < 5; j++) {
twod[i][j] = k;
k++;
}
for (i = 0; i < 4; i++) {
for (j = 0; j < 5; j++)
System.out.print(twod[i][j] + " ");
System.out.println();
}
}
}
The result it generates is
0 1 2 3 4
5 6 7 8 9
10 11 12 13 14
15 16 17 18 19
Try this :
public class TwoDimensional {
private int i, j, k = 0;
int[][] twod = new int[4][5];
public void DoubleT() {
for (i = 0; i < 4; i++)
for (j = 0; j < 5; j++) {
twod[i][j] = k;
k++;
}
}
for (i = 0; i < 4; i++) {
for (j = 0; j < 5; j++){
System.out.print(twod[i][j] + " ");
}
System.out.println();
}
}
To properly use the braces always think about the purpose of the loops you have, when do you want them to finish and when do you want them to continue.
In your case, you'll need nested loops for different tasks so you have to properly delimit each one of those tasks.
Fill the the 2D array:
for (i = 0; i < 4; i++)
for (j = 0; j < 5; j++) {
twod[i][j] = k;
k++;
}
}
Print the 2D array values:
for (i = 0; i < 4; i++) {
for (j = 0; j < 5; j++){
System.out.print(twod[i][j] + " ");
}
System.out.println();
}
Notice that, either for filling or printing the array, your first loop (iterator i) is responsible for the line. It'll stop at I = 3, line number 3. So you'll be in line 0 until you finish the values of all the columns on that line ( [0][0],[0][1],[0][2],[0][4] ) and you just want to go to the second line when your first line is totally filled or printed, and so on. On the print case, you'll need to change the line before the 'i' increments (new line number) and after you have all `'j' values.
To summarize, you'll just want to increment the line ('i') or go to the next line (println()), when your columns ('j') are finished.
Related
I have to print the following numbers using nested loops, and I kinda have an idea how, but not how to execute it.
000111222333444555666777888999
000111222333444555666777888999
000111222333444555666777888999
My code so far is something like:
public class opgave_2 {
public static void main(String[] args) {
final int first = 3;
final int second = 3;
final int third = 9;
for (int i = 0; i <= first ; i++) {
for (int j = i; j <= second; j++) {
for (int k = j; k <= third; k++) {
System.out.print(i);
}
}
}
}
}
You should proceed by steps to resolve such problem.
First, you want to print a number 3 times :
int myNumber = 0;
for(int i=0; i<3; i++) {
System.out.print(myNumber);
}
Second, you want to repeat it 9 times and your number to vary from 0 to 9 (seems like an index of loop) :
for(int myNumber=0; myNumber<=9; myNumber++) {
for(int i=0; i<3; i++) {
System.out.print(myNumber);
}
}
Third, you want to display this line 3 times :
for(intj=0; j<3; j++) {
for(int myNumber=0; myNumber<=9; myNumber++) {
for(int i=0; i<3; i++) {
System.out.print(myNumber);
}
}
System.out.println(""); //new line
}
What about something like this:
for (int i = 0; i < 3; i++) {
for (int j = 0; j <= 9; j++) {
System.out.printf("%1$s%1$s%1$s", j);
}
System.out.println();
}
Which uses 2 nested loops. The first to print the line 3 times, and the second to print the numbers per line
you can use a loop, that loops 3 times. in that you put a loop that prints every number from 0 to 9 3 times in a row within the same line
for(int a = 0; a < 3; a++){
for(int i = 0; i < 10; i++){
System.out.print(i+""+i+""+i);
}
System.out.println(); //for the new line
}
or
for(int a = 0; a < 3; a++){
for(int i = 0; i < 10; i++){
System.out.print(i);
System.out.print(i);
System.out.print(i);
}
System.out.println(); //for the new line
}
this should do
I can't understand how nested for loop works. Just doing ascending order program please explain me step by step how it works
class Ascending {
public static void main(String args[]) {
int temp;
int a[] = {20, 10, 80, 70};
for (int i = 0; i < 4; i++) {
System.out.println(a[i]);
}
for (int i = 0; i < 4; i++) {
for (int j = i + 1; j < 4; j++) {
if (a[i] > a[j]) {
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
}
System.out.println("\n after:");
for (int i = 0; i < 4; i++) {
System.out.println(a[i]);
}
}
}
Output:
20
10
80
70
after:
10
20
70
80
How nester loops are working.
Well this is quite simple, a for loop is define as follow :
for(init;condition;increment)
init : is executed once at the beginning
condition : check before every execute (like a while)
increment : will be done after the code in the loop
Here, with one loop,
for (int i = 0; i < 4; i++) {
// code
}
This will be the same as
int i = 0;
while(i < 4){
// code
i++;
}
If you have nested loops, the idea is the same, the inner loop will need to execute as many time as the condition is true before the outer one can increment and check his condition again.
for (int i = 0; i < 4; i++) { //loop A
for (int j = i + 1; j < 4; j++) { //loop B
// code
}
}
loop A will start with i = 0, then loop B will start with j = i = 0.
The code will be execute until j => 4 to exit loop B. There, loop A will execute the increment part, i = 1.
The condition is still true so the loop will execute his code, the loop B will start with j = i = 1.
And again ... until loop A's condition is false.
I need to create a nested for loops that gives the following output,
0
1
2
3
This is what I have, but for the second test, userNum is replaced by 6 and obviously my code fails.. help?
public class NestedLoop {
public static void main (String [] args) {
int userNum = 0;
int i = 0;
int j = 0;
for(i = 0; i <= userNum; i++){
System.out.println(i);
for(i = 1; i <= userNum; i++){
System.out.println(" " +i);
for(i = 2; i <= userNum; i++){
System.out.println(" " +i);
for(i = 3; i <= userNum; i++){
System.out.println(" " + i);
}
}
}
}
return;
}
}
I think (it's a guess, though) that you're looking for this.
public static void main (String [] args)
{
int limit = 6;
for(int i = 0; i <= limit; i++)
{
for(int j = 0; j < i; j++)
System.out.print(" ");
System.out.println(i);
}
}
The reason why your approach fails is, as I see it, that you are looping through the numbers to show (which is right) but you fail to loop up on the number of spaces (which I resolved by relating the inner loop's limit to the outer loop's current value.
Let's talk a bit about what your intention is with these loops.
The inner loop is meant to produce an arbitrary number of spaces, depending on what number you're iterating on. So if you're on number 0, you produce no spaces, and if you're on 1, you produce one space, and so forth. The other caveat is that they all must appear on the same line, so System.out.println is the incorrect choice.
You would want to use System.out.print to print out the spaces. So let's write that.
for(int j = 0; j < 6; j++) {
System.out.print(" ");
}
This will print out six spaces unconditionally. What that condition is depends on the current number we're iterating on. That comes from your outer loop.
You only need to define a loop that starts from an arbitrary starting point - like 0 - and then loop until you are at most your ending number. For this, your current loop is sufficient:
for(i = 0; i <= userNum; i++) {
}
Now, we need to bring the two pieces together. I leave the figuring out of the question mark and what to print after you've printed the spaces as an exercise to the user, bearing in mind that you must stop printing spaces after you've reached your number.
for(int i = 0; i <= userNum; i++) {
for(int j = 0; j < ?; j++) {
System.out.print(" ");
}
}
Let's analyse the task
In every line, we should print a number and different number spaces in the front of the number.
For that, we need two loops - one outer to iterate from 0 to N and one inner to add spaces in front of the number.
private static void method1(int userNum) {
int nummSpaces = 0;
for (int i = 0; i <= userNum; i++) {
for (int j = 0; j < nummSpaces; j++) {
System.out.print(" ");
}
nummSpaces++;
System.out.println(i);
}
}
In this solution, we have variable numSpaces which used to count the number of spaces in front of the number. It is unneeded - we can use variable i for that purpose.
private static void method2(int userNum) {
for (int i = 0; i <= userNum; i++) {
for (int j = 0; j < i; j++) {
System.out.print(" ");
}
System.out.println(i);
}
}
Let's analyses once again the output
- the fist line: printed zero spaces and number 0
- the second line: printed one space and number 1
- the third line: printed two spaces and number 2
- and so on
Finally, we can use just one variable, which contains spaces and after that print the length of it:
private static void method3(int userNum) {
for (String spaces = ""; spaces.length() <= userNum; spaces += " ") {
System.out.println(spaces + spaces.length());
}
}
C/C++
#include <iostream>
using namespace std;
int main() {
int userNum;
int i;
int j;
cin >> userNum;
for (i = 0; i <= userNum; ++i) {
for (j = 0; j < i; ++j) {
cout << " ";
}
cout << i << endl;
}
return 0;
}
I have an array called blockHeights, which contains 3 values inside of it, namely 1,2,3. So blockHeights[0] is equal to 1.
I also have a loop:
for (int i = 1; i <= blockHeights.length; i++)
In the first time around the loop, I want to create a variable called totalBlockHeights where it is
int totalBlockHeights = blockHeights[0] + blockHeights [1] + blockHeights [2];
However, in the next loop I want that variable to change, so that it only adds blockHeights[1] and blockHeights[2] together, ignoring blockHeights[0].
How would I go about doing this?
Try the following (I'm assuming the third iteration should only include blockHeights[2], following the pattern):
for (int i = 1; i <= blockHeights.length; i++) {
int totalBlockHeights;
for (int j = i - 1; j < blockHeights.length; j++) { // all block heights from here onwards
totalBlockHeights += blockHeights[j];
}
// do whatever
}
Well, if you want the sum of your array, and the sum of the array without first value
int totalBlockHeights = 0;
for(int i = 0; i < blockHeights.length; i++){
totalBlockHeights += blockHeights[i];
}
System.out.println(totalBlockHeights);
System.out.println("totalBlockHeights without first value = " + (totalBlockHeights - blockHeights[0]));
this way you only loop once
Try following code:
public class Loop {
public static void main(String[] argv) {
int[] blockHeights = new int[] {1, 2, 3};
int totalBlockHeights = 0;
for(int i = 0; i < blockHeights.length; i++) {
totalBlockHeights = 0;
for(int j = i; j < blockHeights.length; j++) {
totalBlockHeights += blockHeights[j];
}
System.out.println(totalBlockHeights);
}
}
}
int[] blockHeights = new int[] { 1, 2, 3 };
int totalBlockHeights = 0;
int customBlockHeights = 0;
for (int i = 0; i < blockHeights.length; i++) {
totalBlockHeights += blockHeights[i];
if (i == 0) {
continue;
}
customBlockHeights += blockHeights[i];
}
System.out.println(totalBlockHeights);
System.out.println(customBlockHeights);
This will print:
6
5
You dont need two for to achieve that.
you can perform this on two for loop outer loop for (int i = 1; i <= blockHeights.length; i++), and in inner loop (take a variable j) you can do like int totalBlockHeights = totalBlockHeights + blockHeights[j], and for i<j, you can just continue the for loop.
as answered by btrs20
My professor wants me to print out the matrices side by side with the "+" between the two matrices and then a "=" sign. In the end he wants us to add the matrices together.
This is the work so far.
So the result would come out as:
1 2 3 9 8 7 10 10 10
4 5 6 + 6 5 4 = 10 10 10
7 8 9 3 2 1 10 10 10
enter code here public static void main(String[] args) {
int matrix1[][] = {{1,2,3},{4,5,6},{6,7,8}};
int matrix2[][] = {{9,8,7},{6,5,4},{3,2,1}};
int result1;
int[][] result2 = new int[2][3];
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[0].length; j++) {
System.out.printf(matrix1[i][j] + " ");
System.out.print("");
}
System.out.println("");
}
for (int i = 0; i < matrix2.length; i++) {
for (int j = 0; j < matrix2[0].length; j++) {
System.out.printf(matrix2[i][j] + " ");
}
System.out.println("");
}
}
My problem is, how could I print it side by side with the solutions?
Consider the two printing loops for your matrices:
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[0].length; j++) {
System.out.printf(matrix1[i][j] + " ");
}
System.out.println("");
}
for (int i = 0; i < matrix2.length; i++) {
for (int j = 0; j < matrix2[0].length; j++) {
System.out.printf(matrix2[i][j] + " ");
}
System.out.println("");
}
They print matrix 1, then 2 - and so the matrices will be below each other.
If you want the matrices side by side, you need to print line 1 of every matrix, then - after a new line - line 2 of every matrix, etc. By re-arranging how the loops go through the matrices, you could have your new layout.
You unfortunately cannot print them one at a time, you need to take it row by row. This solution requires both matrix1 and matrix2 to be of equal height. But here's a template that should get you started.
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[i].length; j++) {
}
if (i == matrix1/2) {
} else { //One part of if handles when "+" is needed, other one doesn't
}
for (int j = 0; j < matrix2[i].length; j++) {
}
if (i == matrix1/2) {
}
for (int j = 0; j < ???; j++) {
}
}