I need some help. I want to achieve a result as shown on my image result
first question... did my teacher make a mistake? 2^10 = 1024 and not 2048... ?! but nvm..
my only problem is the cout of numbers over 100.000 - please help
here's my code so far
#include <iostream>
#include <math.h>
#include <iomanip>
#include <string>
#include <sstream>
#include <ostream>
#include <stdio.h>
#include <conio.h>
#include <fstream>
using namespace std;
int main() {
int p; // exponent
float b; // base
cout << setw(4);
for (b=1; b<11; b++) {
cout << " | " << setw(12) << b;
}
cout << endl;
for (b=1; b<=10; b++) {
cout << b;
for (p=1; p<=10; p++) {
cout << " | " << setw(12) << pow(b, p);
}
cout << endl;
}
return 0;
}
Output of this is here
pls pls help,
best regards!
If the issue is output, then the easiest thing to do is cast the pow() return value to a long long or whatever your compiler's 64-bit int type is.
This will automatically use the long long overload for operator <<, which will effectively remove the scientific notation.
for (p=1; p<=10; p++) {
cout << " | " << static_cast<long long>(pow(b, p));
Live Example
Related
im new to programming and was trying to understand buffers and came across :
https://www.tutorialspoint.com/what-does-buffer-flush-means-in-cplusplus#:~:text=The%20buffer%20flush%20is%20used,the%20buffer%20to%20be%20written.
it said that if the buffer is not flushed, the numbers will be printed at once while it will be printed one after the other while flushing the buffer.But after trying it on my computer, they both printed one after the other.
idk this might be a silly question
#include <iostream>
#include <thread>
#include <chrono>
using namespace std;
main() {
for (int x = 1; x <= 5; ++x) {
cout << x << " " << flush;
this_thread::sleep_for(chrono::seconds(1)); //wait for 1 second
}
cout << endl;
}
#include <iostream>
#include <thread>
#include <chrono>
using namespace std;
main() {
for (int x = 1; x <= 5; ++x) {
cout << x << " ";
this_thread::sleep_for(chrono::seconds(1)); //wait for 1 second
}
cout << endl;
}
How to increment a column of a dynamic matrix by one, as an in place operation (without creating copies/intermediates) ?
Attempt:
#include <Eigen/Dense>
#include <iostream>
#include <stdint.h>
int main(void){
Eigen::MatrixXf A;
A = Eigen::MatrixXf::Random(3, 5);
std::cout << A << std::endl << std::endl;
A.col(1) = A.col(1)*2; //this works.
A.col(1) = A.col(1) + 1; //this doesn't work.
std::cout << A << std::endl;
}
I found a way to do this. But I don't know if the operation is in place.
This is similar to eigen: Subtracting a scalar from a vector
#include <Eigen/Dense>
#include <iostream>
int main(void){
Eigen::MatrixXf A;
A = Eigen::MatrixXf::Random(3, 5);
std::cout << A << std::endl << std::endl;
A.col(1) = A.col(1)*2;
A.col(1) = A.col(1) + Eigen::VectorXf::Ones(3);
std::cout << A << std::endl;
}
Another way is to use array operation. This way seem better (I guess).
https://eigen.tuxfamily.org/dox/group__TutorialArrayClass.html
#include <Eigen/Dense>
#include <iostream>
int main(void){
Eigen::MatrixXf A;
A = Eigen::MatrixXf::Random(3, 5);
std::cout << A << std::endl << std::endl;
A.array() += 1;
A.col(1).array() += 100;
std::cout << A << std::endl;
}
#include <iostream>
#include <vector>
#include <iterator>
#include <iostream>
#include <cmath>
#include <string>
#include <utility>
#include <cstring>
#include <list>
using std::vector;
using std::cout;
using std::list;
using std::endl;
using std::string;
using namespace std;
template <typename T>
void showContents(T& input)
{
typename T::iterator it;
for (it=input.begin(); it != input.end(); it++)
{ cout << *it << " "; }
cout << endl;
}
int main()
{
int B[10] = {0,1,2,3,4,5,6,7,8,9};
cout<< "The first array is: "<< "\n";
int i;
for (i = 0; i<10; i++)
{cout<< B[i]<< " ";}
vector<int> KVec(B,B+10);
cout << "\n \n" << "The first vector is: " << endl;
showContents(KVec);
list<int> BList(B,B+10);
cout << "\n" << "The first list is: " << endl;
showContents(BList);
int BCopy [10];
cout<< "\n" <<"The second array is: "<< endl;
for(int i = 0; i <10; i++)
{
BCopy[i] = B[i];
BCopy[i] += 2;
cout<< BCopy[i]<< " ";
}
vector<int> KVec2(KVec);
cout<< "\n \n" << "The second vector is: "<< endl;
for (int i = 0; i<KVec2.size(); i++){
KVec2[i] += 3;
}
showContents(KVec2);
cout<< "\n" << "The second list is: "<< endl;
std::list<int> BList2 (BList);
for (std::list<int>::iterator b = BList.begin(); b!=BList.end(); ++b)
{
( *b += 5 );
showContents(BList2);
}
This is the code I have. I was able to correctly copy all the arrays, vectors , and lists and increasing the values of those accordingly. The only one I have not been able to increment in the list. My goal is to increment all the elements of the second list by 5. I have been using mulitple references to try and do it but I have tried everything and can not get it to work. Below I have my latest attempt at trying to increment all the values but that doesn't seem to work either so now I need help. That is the only thing left to do in this assignment so any help would be appreciated. Thank you.
Since my comment fixed your problem, I am converting it into an answer.
You copy constructed BList2 using values from BList (I am changing to brace initialization to avoid Most vexing parse). But then, you are iterating over values of BList again. Also, you don't need parentheses around *b += 5. Finally, your showContents function is probably meant to be outside of the loop.
std::list<int> BList2 {BList};
for (std::list<int>::iterator b = BList2.begin(); b != BList2.end(); ++b)
{
*b += 5;
}
showContents(BList2);
I would like to see whether it is possible to see all values that we have emplaced. For example:
#include <iostream>
#include <unordered_map>
using namespace std;
int main () {
unordered_multimap<string,int> hash;
hash.emplace("Hello", 12);
hash.emplace("World", 22);
hash.emplace("Wofh", 25);
for (int i = 1; i < 10; i++) {
hash.emplace("Wofh", i);
}
cout << "Hello " << hash.find("Hello")->second << endl;
cout << "Wofh " << hash.count("Wofh") << endl;
cout << "Wofh " << hash.find("Wofh")->second << endl;
return 0;
}
The output is :
$ ./stlhash
Hello 12
Wofh 10
Wofh 9
Whereas I want the last line to show from 25,1,2... to 9. Apparently find only takes first and second pointer as first is the value and second is the corresponding value. Is there any way to do this?
The operation you need is called equal_range
Example from the cplusplus.com:
// unordered_multimap::equal_range
#include <iostream>
#include <string>
#include <unordered_map>
#include <algorithm>
typedef std::unordered_multimap<std::string,std::string> stringmap;
int main ()
{
stringmap myumm = {
{"orange","FL"},
{"strawberry","LA"},
{"strawberry","OK"},
{"pumpkin","NH"}
};
std::cout << "Entries with strawberry:";
auto range = myumm.equal_range("strawberry");
for_each (
range.first,
range.second,
[](stringmap::value_type& x){std::cout << " " << x.second;}
);
return 0;
}
Is there a way to round to the nearest number in the Boost library? I mean any number, 2's, 5's, 17's and so on and so forth.
Or is there another way to do it?
You can use lround available in C99.
#include <cmath>
#include <iostream>
int main() {
cout << lround(1.4) << "\n";
cout << lround(1.5) << "\n";
cout << lround(1.6) << "\n";
}
(outputs 1, 2, 2).
Check your compiler documentation if and/or how you need to enable C99 support.
Boost Rounding Functions
For example:
#include <boost/math/special_functions/round.hpp>
#include <iostream>
#include <ostream>
using namespace std;
int main()
{
using boost::math::lround;
cout << lround(0.0) << endl;
cout << lround(0.4) << endl;
cout << lround(0.5) << endl;
cout << lround(0.6) << endl;
cout << lround(-0.4) << endl;
cout << lround(-0.5) << endl;
cout << lround(-0.6) << endl;
}
Output is:
0
0
1
1
0
-1
-1
int nearest = 5;
int result = (input+nearest/2)/nearest*nearest;
You actually don't need Boost at all, just the C library included in the C++ library. Specifically, you need to include the cmath header:
Round up a number: ceil(): http://www.cplusplus.com/reference/clibrary/cmath/ceil/
Round down a number: floor(): http://www.cplusplus.com/reference/clibrary/cmath/floor/
You can write your own round function then:
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <utility>
double roundFloat(double x)
{
double base = floor( x );
if ( x > ( base + 0.5 ) )
return ceil( x );
else return base;
}
int main()
{
std::string strInput;
double input;
printf( "Type a number: " );
std::getline( std::cin, strInput );
input = std::atof( strInput.c_str() );
printf( "\nRounded value is: %7.2f\n", roundFloat( input ) );
return EXIT_SUCCESS;
}