There are two lines of out for every iteration of the loop. I want for line a to be on top of line b in every iteration. Moreover, I want to display the next (i=1) iterated line a and b to be horizontal with the previous (i=0) line a and b.
for (int i = 0; i < 2; ++i){
cout << "LOOP" << endl; //line a
cout << i << endl; //line b
}
Current output:
LOOP
0
LOOP
1
Desired output:
LOOP LOOP
0 1
You can keep the logic of your program as it is and store the output in a buffer before sending it to stdout.
For example you can use a std::ostringstream for every line:
#include <iostream>
#include <sstream>
#include <iomanip>
int main() {
std::ostringstream line_a,
line_b;
for (int i = 0; i < 4; ++i) {
line_a << std::setw(6) << "LOOP";
line_b << std::setw(6) << i;
}
std::cout << line_a.str() << '\n'
<< line_b.str() << '\n';
return 0;
}
You can do
for (int i = 0; i < 2; ++i) {
cout << "LOOP\t";
}
cout << endl;
for (int i = 0; i < 2; ++i) {
cout << i << "\t";
}
Related
I am struggling with printing an array with 4 rows and 4 columns, when I initialized the array and entered all the values. Then, I used for loop to get all the values together so I can print them. But I get is an array that companied all the values in one row.
I have attached the output when I run the code.
Here is a portion of my code, it is long code but I am struggling in specific part:
#include <iostream>
using namespace std;
int main()
{
cout << "The martix before I flipped it: " << endl;
cout << endl;
int array[4][4] = { 16,3,2,13,5,10,11,8,9,6,7,12,4,5,14,1 };
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
cout << array[i][j] << " ";
}
}
return 0;
The standard output utility std::cout is a stream from the stl and, as such, its << operator does not usually automagically append a linebreak.
Which is quite practical since, otherwise, you would not be able to print multiple numbers on a single line.
That being, said, you'll need to add the linebreak manually, like so :
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
std::cout << array[i][j] << " ";
}
std::cout << std::endl;
}
Alternatively, you can consider printing lines 4 at a time since your matrix is of constant size :
for (int i = 0; i < 4; i++) {
std::cout << array[i][0] << " "
<< array[i][1] << " "
<< array[i][2] << " "
<< array[i][3] << " " << std::endl;
}
Have a great day,
Currently I have a pre-made 6X6 matrix in a text file like this:
2 6 3 1 0 4
4 2 7 7 2 8
4 7 3 2 5 1
7 6 5 1 1 0
8 4 6 0 0 6
1 3 1 8 3 8
and I made a code that is reading from a file i have made. However I want to have user make a grid for themselves (i.e. 3X3 or 10X10). Which then writes to a text file automatically like in similar fashion and then have that read-in instead. It is a basic memory match card game, so I need to have rand() which generates equal pair so the game can be over when every pair in the grid has been found. Thank you so much for your time!
/*Here are the snippets of my code*/
#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <vector>
#include <fstream>
#include <string>
#include <numeric>
#include <limits>
using namespace std;
//global 2d vectors that are associated with the game
vector<vector<int> > game_grid;
vector<vector<int> > hidden_grid;
vector <vector<int> > guessed;
void initialize_grid() {
ifstream input_file;
input_file.open("grid.txt");
int num;
if (input_file) {
for (int i = 0; i < 6; ++i) {
vector<int> row; // game grid
vector<int> row2; // hidden grid
vector<int> row3; // guessed grid
for (int j = 0; j < 6; ++j) {
if (input_file >> num)
row.push_back(num);
row2.push_back(-1);
row3.push_back(0);
}
game_grid.push_back(row);
hidden_grid.push_back(row2);
guessed.push_back(row3);
}
cout << "Get is ready, Challenger!" << endl << endl;
}
else {
cout << "Womp. File open failed!";
}
return;
}
void print_grid() {
cout << "Game grid" << endl;
cout << " -------------------------" << endl;
for (int i = 0; i < 6; ++i) {
cout << " | ";
for (int j = 0; j < 6; ++j) {
cout << game_grid[i][j] << " | ";
}
cout << endl << " -------------------------" << endl;
}
cout << endl;
}
void print_hidden_grid(int r1 = -1, int r2 = -1, int c1 = -1, int c2 = -1) {
cout << "Attempt:" << endl;
if (r1 != -1) {
hidden_grid[r1][c1] = game_grid[r1][c1];
}
if (r2 != -1) {
hidden_grid[r2][c2] = game_grid[r2][c2];
}
for (int i = 0; i < 6; ++i) {
cout << " | ";
for (int j = 0; j < 6; ++j) {
if (hidden_grid[i][j] > -1)
cout << hidden_grid[i][j] << " | ";
else
cout << " | ";
}
cout << endl << " -------------------------" << endl;
}
cout << endl;
if (r1 != -1) {
if (game_grid[r1][c1] == game_grid[r2][c2]) {
guessed[r1][c1] = 1;
guessed[r2][c2] = 1;
cout << "You have a match!" << endl << endl;
}
else {
hidden_grid[r1][c1] = -1;
hidden_grid[r2][c2] = -1;
}
}
cout << endl << endl;
}
void print_current_grid() {
cout << "Current Grid:" << endl;
cout << " -------------------------" << endl;
for (int i = 0; i < 6; ++i) {
cout << " | ";
for (int j = 0; j < 6; ++j) {
if (hidden_grid[i][j] > -1)
cout << hidden_grid[i][j] << " | ";
else
cout << " | ";
}
cout << endl << " -------------------------" << endl;
}
cout << endl << endl;
}
.......
If I well understand you want to auto detect the size of the matrix when you read it ? If yes you can do something like that in initialize_grid :
void initialize_grid() {
ifstream input_file;
input_file.open("grid.txt");
int num;
if (input_file) {
// detect size
int size = 0;
string line;
if (!getline(input_file, line))
return;
istringstream iss(line);
while (iss >> num)
size += 1;
input_file.clear();
input_file.seekg(0);
for (int i = 0; i < size; ++i) {
vector<int> row; // game grid
vector<int> row2; // hidden grid
vector<int> row3; // guessed grid
for (int j = 0; j < size; ++j) {
if (input_file >> num)
row.push_back(num);
row2.push_back(-1);
row3.push_back(0);
}
game_grid.push_back(row);
hidden_grid.push_back(row2);
guessed.push_back(row3);
}
cout << "Get is ready, Challenger!" << endl << endl;
}
else {
cout << "Womp. File open failed!";
}
}
and else where you replace 6 by game_grid.size() (using size_t rather than int to type the indexes)
I want to cout an array as a row vector but when I write:
int main() {
int B[3]={0};
for (int w = 0; w <2; w++) {
cout <<"B="<<" "<< B[w] << " ";
}
cout << endl;
return 0;
}
The output is B=0 B=0
But I want output to be like:
B=(0 0)
For a fixed size array of only I would probably even prefer a oneliner like this, because I can read it at first glance:
cout << "B=(" << B[0] << " " << B[1] << " " << B[2] << ")\n";
For a container B with a dynamic or very high number of elements n, you should probably do something like this:
cout << "B=(";
if(n > 0)
{
cout << B[0];
// note the iteration should start at 1, because we've already printed B[0]!
for(int i=1; i < n; i++)
cout << ", " << B[i]; //I've added a comma here, so you get output like B=(0, 1, 2)
}
cout << ")\n";
This has the advantage, that no matter what number of elements, you don't end up with trailing commas or unwanted whitespace.
I'd reccommend making a generic (template) function for the purpose of printing array/std::vector content anyways - it's really useful for debugging purposes!
int main() {
int B[3] = { 0 };
cout << "B=(";
for (int w = 0; w < 3; w++) {
cout << B[w];
if (w < 2) cout << " ";
}
cout << ")" << endl;
return 0;
}
Output should be now:
B=(0 0 0)
The simplest way to do this is:-
#include<iostream>
using namespace std;
int main()
{
int B[3]={0};
cout << "B=(";
for (int w = 0; w < 3; w++)
{
cout << B[w] << " ";
}
cout << ")" << endl;
return 0;
}
the output will be B= (0 0 0 )
You can try this one if you want:
#include <iostream>
using namespace std;
int main() {
int B[3]={0};
cout << "B=(";
for (int w = 0; w <2; w++) {
cout << B[w];
if(w != 1) cout << " ";
}
cout << ")" << endl;
cout << endl;
return 0;
}
The output is:
B=(0 0)
The line if(w != 1) checks whether you 've reached the last element of the array. In this case the last index is 1, but in general the if statement should be: if(w != n-1) where n is the size of the array.
I'm trying to do some of my C++ homework, but I seem to have run into an issue. I need to make it so that the user inputs 8 numbers, and those said 8 get stored in an array. Then, if one of the numbers is greater than 21, to output said number. The code is below, and it's kind of sloppy. Yes, first year C++ learner here :p
#include <iostream>
using namespace std;
int main() {
const int NUM_ELEMENTS = 8; // Number of elements
int userVals[NUM_ELEMENTS]; // User numbers
int i = 0; // Loop index
int sumVal = 0; // For computing sum
int prntSel = 0; // For printing greater than 21
// Prompt user to populate array
cout << "Enter " << NUM_ELEMENTS << " integer values..." << endl;
for (i = 0; i < NUM_ELEMENTS; ++i) {
cin >> userVals[i];
}
for (int i = NUM_ELEMENTS - 1; i > 21; i--)
cout << "Value: " << sumVal << endl;
// Determine sum
sumVal = 0;
for (i = 0; i < NUM_ELEMENTS; ++i) {
sumVal = sumVal + userVals[i];
}
cout << "Sum: " << sumVal << endl;
return 0;
}
Don't reinvent the wheel, use standard algorithms:
std::copy_if(std::begin(userVals), std::end(userVals),
std::ostream_iterator<int>(std::cout, "\n"),
[] (auto x) { return x > 21; });
I improved the rest of your program as well:
#include <algorithm>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>
auto constexpr count = 8;
int main() {
std::vector<int> numbers(count);
std::cout << "Enter " << count << " integer values...\n";
std::copy_n(std::istream_iterator<int>(std::cin), numbers.size(), numbers.begin());
std::copy_if(numbers.begin(), numbers.end(),
std::ostream_iterator<int>(std::cout, "\n"),
[] (auto x) { return x > 21; });
auto sum = std::accumulate(numbers.begin(), numbers.end(), 0);
std::cout << "Sum: " << sum << '\n';
return 0;
}
See it live on Coliru!
Ok, I'm going to explain this to you and keep it simple. This loop
`for (int i = NUM_ELEMENTS - 1; i > 21; i--)`
will never execute because in your first iteration you are checking if (NUM_ELEMENTS-1=7)>21. You are then decrementing i so this will take the series (6,5,4,...) and nothing would ever happen here.
If you have to sum the numbers greater than 21, which I presume is what you need then you will have to remove the above loop and modify your second loop to:
for (i = 0; i < NUM_ELEMENTS; i++) {
if(userVals[i]>21)
sumVal = sumVal + userVals[i];
}
This way, you add the numbers in the array that are only greater than 21. The index of userVals is determined by the i variable which also acts as a counter.
You're on the right track. There's just a few things wrong with your approach.
#include <iostream>
#include <stdlib.h>
using namespace std;
int main() {
const int NUM_ELEMENTS = 8;
int userVals[NUM_ELEMENTS];
int i = 0;
int sumVal = 0;
int prntSel = 0;
int size = sizeof(userVals) / sizeof(int); // Get size of your array
// 32/4 = 8 (ints are 4 bytes)
cout << "Enter " << NUM_ELEMENTS << " integer values..." << endl;
for (i = 0; i < NUM_ELEMENTS; ++i) {
cin >> userVals[i];
}
for(int i = 0; i < size; i++) {
if(userVals[i] > 21) { // Is number > 21?
cout << userVals[i] << endl; // If so, print said number
exit(0); // And exit
}
else
sumVal += userVals[i]; // Else sum your values
}
cout << "Sum: " << sumVal << endl;
return 0;
}
#include <iostream>
using namespace std;
int main() {
const int NUM_ELEMENTS = 8; // Number of elements
int userVals[NUM_ELEMENTS]; // User numbers
int i = 0; // Loop index
int sumVal = 0; // For computing sum
int prntSel = 0; // For printing greater than 21
// Prompt user to populate array
cout << "Enter " << NUM_ELEMENTS << " integer values..." << endl;
for (i = 0; i < NUM_ELEMENTS; ++i) {
cin >> userVals[i];
}
// for (int i = NUM_ELEMENTS - 1; i > 21; i--)
// cout << "Value: " << sumVal << endl;
for( i = 0; i < NUM_ELEMENTS; ++i )
{
if( userVals[ i ] > 21 )
{
cout << "Value: " << i << " is " << userVals[ i ] << endl;
}
}
for (i = 0; i < NUM_ELEMENTS; ++i) {
sumVal = sumVal + userVals[i];
}
cout << "Sum: " << sumVal << endl;
return 0;
}
Try
for (int i = NUM_ELEMENTS - 1; i > 21; i--)
cout << "Value: " << sumVal << endl;
to
for (i = 0; i < NUM_ELEMENTS; ++i) {
if(userVals[i] > 21)
cout << "Value: " << userVals[i] << endl;
}
This line isnt needed as well, as you arent using it.
int prntSel = 0; // For printing greater than 21
for (int i = NUM_ELEMENTS - 1; i > 21; i--)
cout << "Value: " << sumVal << endl;
Here you are printing the value of sumVal, not the value of the array in the position i. The line should be:
cout << "Value: " << usersVals[i] << endl;
Also that that your for is not doing what you think it does. for doesn't use the condition you gave to decide if will execute the current iteration or not, it uses the condition to decide if the loop should continue or not. So when you put i > 21, means that it will continue running while i is bigger than 21. To achieve your goal, you should make a test (if statement) inside the loop.
The final result it would be:
for (i = 0; i < NUM_ELEMENTS; ++i) {
if (usersVals[i] > 21) {
cout << "Value: " << usersVals[i] << endl;
}
}
i wrote a simple program(C++) that take 20 numbers and sort them into ascending order.Now i want to save the actions in the program in a file like "num.txt" with . Can you explain me what changes should i do?
#include <iostream>
#include <iomanip>
#include <conio.h>
using namespace std;
int main() {
int x[21], s;
int j,i;
for (int i = 1; i < 21; i++)
{
cout << setw(11) << i << ": ";
cin >> x[i];
}
for (int i = 1; i < 21; i++)
{
for (int j = i+1; j < 21; j++)
{
if (x[j] < x[i])
{
s = x[j];
x[j] = x[i];
x[i] = s;
}
}
}
cout << endl;
for (int i = 1; i < 21; i++)
{
cout << i << ": ";
cout << x[i] << "\t";
if (i % 5 == 0)
{
cout << endl;
}
}
getch();
return 0;
}
i know it's simple but i just started since few days ago and i'm novice.
To output the numbers to a file you can use std::ofstream for the output stream and replace cout with the variable name you use for the stream.
std::ofstream outfile;
outfile.open("num.txt");
for (int i = 1; i < 21; i++)
{
outfile << i << ": ";
outfile << x[i] << "\t";
if (i % 5 == 0)
{
outfile << std::endl;
}
}
outfile.close();
You can also take it a step further and add input validation and use components from the Standard Library to handle most of what you are trying to accomplish. For instance instead of storing the numbers in an array I suggest using std::vector instead. You can also use std::sort to sort the data instead of implementing it yourself.
#include <vector> // vector
#include <fstream> // fstream
#include <algorithm> // sort
#include <iostream>
int main()
{
std::vector<int> numbers;
while(numbers.size() != 20)
{
int value;
if(!(std::cin >> value))
{
std::cout << "you must enter a number" << std::endl;
}
else
{
numbers.push_back(value);
}
}
// Do the sort. Pretty easy huh!
std::sort(numbers.begin(), numbers.end());
std::ofstream outfile;
outfile.open("num.txt");
if(outfile.is_open() == false)
{
std::cout << "Unable to open num.txt" << std::endl;
}
else
{
for(size_t i = 0; i < numbers.size(); i++)
{
outfile << i << ": ";
outfile << numbers[i] << "\t";
if (i % 5 == 0)
{
outfile << std::endl;
}
}
outfile.close();
}
}
Use this in your code
#include <fstream>
ofstream outputFile;
outputFile.open("outputfile.txt");
outputFile << value << endl;
outputFile.close();
One solution is to use ofstream (in "fstream.h", very similar to std::cout):
ofstream out("num.txt");
if (out.is_open() == false)
{
cout << "Error! Couldn't open file!" << endl;
}
else
{
out << "\n";
for (int i = 1; i < 21; i++)
{
out << i << ": ";
out << x[i] << "\t";
if (i % 5 == 0)
{
out << "\n";
}
}
out.close();
}
If you're running your program from the command line, type the following(when you run it) to forward the output to a file:
myApp > num.txt
you can also use the < switch to specify a file to get input from too
You can find more information here.
here is your code with all the changes
now you just need to copy paste (i have made a comment on line i added )
#include <iostream>
#include <iomanip>
#include <conio.h>
#include <fstream>//file stream
using namespace std;
int main() {
int x[21], s;
int j,i;
for (int i = 1; i < 21; i++)
{
cout << setw(11) << i << ": ";
cin >> x[i];
}
for (int i = 1; i < 21; i++)
{
for (int j = i+1; j < 21; j++)
{
if (x[j] < x[i])
{
s = x[j];
x[j] = x[i];
x[i] = s;
}
}
}
ofstream out; //output file stream
out.open("num.txt"); //opening (and creating output file named out
//cout << endl;
for (int i = 1; i < 21; i++)
{
//cout << i << ": ";
out << i << ": "; //printing in output file
// cout << x[i] << "\t";
out << x[i] << "\t"; //printing in output file
if (i % 5 == 0)
{
//cout << endl;
out << endl; //printing in output file
}
}
//getch();
out.close(); //closing output file
return 0;
}