Visual C++ :: Comparison Of 2 Double Values
Dec 27, 2013
I have std::vector of players and each player have its own value. The value is of the type double, but the original value are of the "XX.00".
Now what I'm trying to do is to insert a player into this vector. For that I need to find a place and to find a place I need to compare player value.
So lets say I have a player in the vector whose value is 24.00 and I am trying to insert a player whose value is 25.00. To my surprise MSVC 2010 tells me that:
24.0000000000000 == 25.00000000000
I do aware that comparing double type is not going to work like this, but I would expect not to have such big of a difference. ;-)
Why this comparison is true and how to eliminate such thing?
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Mar 17, 2015
I am trying to compare a double to be within various ranges, but the comparison is not working correctly. Rounding precision is not a concern, because if the value will match the boundaries so rarely, and it is rounding up to the higher range is acceptable. Below is the doe at issue:
if (kq == 2) {
if (fundt[kq-1][ky-1][2-1] < 450,000,000.00) ktti[ky-1][0] = 1;
else if ((fundt[kq-1][ky-1][2-1] >= 450,000,000.00) && (fundt[kq-1][ky-1][2-1] < 525,000,000.00)) ktti[ky-1][0] = 2;
else if ((fundt[kq-1][ky-1][2-1] >= 525,000,000.00) && (fundt[kq-1][ky-1][2-1] < 650,000,000.00)) ktti[ky-1][0] = 3;
else if ((fundt[kq-1][ky-1][2-1] >= 650,000,000.00) && (fundt[kq-1][ky-1][2-1] < 750,000,000.00)) ktti[ky-1][0] = 4;
else if ((fundt[kq-1][ky-1][2-1] >= 750,000,000.00) && (fundt[kq-1][ky-1][2-1] < 850,000,000.00)) ktti[ky-1][0] = 5;
[Code] ....
I know that a triple-dimension array looks complex, but I can guarantee that is a double. The literal constants I am using should automatically be doubles. The subscript of [2-1] looks odd, but this is code I was given to maintain, and that is how it is written elsewhere, so I kept it for consistency. The problem I am having is that when I run this code, all the data I input is less than the 450 million value, but the run falls through all the if and if-else conditions, and the else code is what is actually executed, i.e., I always get six as my result.
I am running on a Sun Sparc, and the compiler used is SunStudio 12. I have tried using variables, with the values listed above assigned to each variable, but it does work either. When I use variables, if the input value is negative, the comparison for less than 450 million works, but any positive input values will through to the else and give me six.
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Mar 24, 2014
I want to compare two double values
double x = 3072.00000000;
double y = 3072.0000000;
when checking with if its not working
if(x==y) it not working
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Mar 6, 2014
Here is code first:
//fp_screen.h
class fp_screen{
public:
double fps;
double xx3;
[Code] .....
fps:1.16922e+006 // this will happen 80%
fps:900 // this is how it should be
if i do cout << "fps:" << (int)screen.fps << endl;
Somethings number is right like 800 or else
put sometimes its 5423423... something.
What is going on here?
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Nov 3, 2012
The following program takes user input into two arrays and should then determine how many items are different by comparing them with a loop. The comparison always show zero correct answers.
#include <iostream>
using namespace std;
const int QUESTION = 20;
//class for testing grades
class TestGrader {
[Code] ....
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Aug 3, 2014
I'm having a pretty weird problem. I've created an unsigned char array for an image buffer:
buffer_rgb = new unsigned char[_w * _h * 3];
memset(buffer_rgb, 0x0, sizeof(unsigned char)* _w * _h * 3);
And I add pixel color values to it like so:
buffer_rgb[i] = ((unsigned char)(col[0] * 255));
buffer_rgb[i + 1] = ((unsigned char)(col[1] * 255));
buffer_rgb[i + 2] = ((unsigned char)(col[2] * 255));
Where col is a 'vec4' struct with a double[4] with values between 0 and 1 (this is checked and clamped elsewhere, and the output is safely within bounds). This is basically used to store rgb and intensity values.
Now, when I add a constant integer as a pixel value, i.e.:
buffer_rgb[i] = ((unsigned char)255;
Everything works as it should. However, when I use the above code, where col is different for every sample sent to the buffer, the resulting image becomes skewed in a weird way, as if the buffer writing is becoming offset as it goes.
These two images illustrate the problem:
tomsvilans.com/temp/140803_render_skew.png
tomsvilans.com/temp/140803_render_noskew.png
You can see in the 'noskew' image all pixels are the same value, from just using an unchanging int to set them. It seems to work with any value between 0-255 but fails only when this value is pulled from my changing col array.
Whole function is here:
// adds sample to pixel. coordinates must be between (-1,1)
void Frame::addSample(vec4 col, double contrib, double x, double y) {
if (x < -1 || x >= 1 || y < -_aaspect || y >= _aaspect) {
[Code] .....
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Nov 4, 2013
I need to write a function that will merge the content of two sorted arrays of type double values. The function should not assume that both its input parameter arrays are the same length.
Here is my program so far - I know there is alot of errors and mistakes:
Code:
#include<stdio.h>
void merge(int firstArray[],int secondArray[],int size) {
int mergedArray[size],i=0,j=0,k=0;
while(i<size||j<size) {
if(i==size) {
[Code]...
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Nov 22, 2013
I have the following piece of code:
string ss = findNodeValue( str, "Horizon");
cout << "ss is: " << ss << endl;
double dd = atof( ss.c_str());
cout << "dd is: " << dd << endl;
When the value of 'ss' is printed, I find it prints 1.0, but when the value of 'dd' is printed, it prints 1 whereas it is supposed to print 1.0.
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Jul 31, 2013
1) What is the range of numbers covered by a 64-bit double?
2) Ignoring fractions, is the above range wider or narrower than the range covered by an int64?
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Sep 5, 2013
I receive a byte stream. The first 8 bytes contain an Identification number. I receive at first the lowest byte and at the end the highest byte of the number. How can I transform this into a double value and later back into the bytestream? In the past I hard only 2 Byte values and there I could use things like MAKEWORD and HIBYTE and LOWBYTE to convert the values
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Oct 25, 2014
When I run the program, when it displays the lowest temtpature, it shows the address instead of the actual number.
Code:
/*********************************************
* File: b.cpp
* Description: Create a C++ program that declares a 100-element array of doubles representing temperature readings. Pass the array to a function to be partially filled by the user. When the user is done entering temperatures, the function should return the number of elements added to the array. The main function should then display the maximum and minimum temperatures in the array.
***********************************************/
#include <iostream>
using namespace std;
//prototypes
void getData(double arr[]);
[Code] ....
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Sep 19, 2012
I'm trying to remake my Windows screensaver written with C++ and WinAPIs to work on multiple monitors. I found this article that gives the basics. But when I implement it in my own code, I get a weird result. Take a look at this code:
Code:
case WM_PAINT: {
PAINTSTRUCT ps = {0};
HDC hdcE = BeginPaint(hWnd, &ps );
EnumDisplayMonitors(hdcE, NULL, MyPaintEnumProc, 0);
EndPaint(hWnd, &ps);
[code]....
Painting always works on a primary monitor. But when I paint to the secondary monitor, I can only paint directly to its DC. When I use double-buffering technique (with DIRECT_PAINT pre-processor directive commented out) I only get a black screen on a secondary monitor when it should've been red.
First one with direct painting that works:
and then the one that doesn't, with double-buffering technique:
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Feb 2, 2015
I need a program that can compare two xml files for equivalency using any XML Parser.
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Mar 6, 2012
I have to compare data in excel and csv based on the file name and update the status of file from CSV into excel file by creating a new column status on weekly basis.
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Oct 30, 2014
I have a small piece of code that used the set::insert function on a set of myClass. For that, I need to overload the < and > operators, which I have, but I still get a huge error saying it can't compare.
set<MyClass> mySet;
MyClass myClass
All the class information gets filled in. Then, I try to insert...
mySet.insert(myClass);
bool operator<(MyClass &lhs, MyClass &rhs) {
return lhs.name < rhs.name; //name is a string
}
The error says
...stl_function.h:230:22: error: no match for 'operator<' in '__x < __y'
MyFile.h:80:6: note: candidate is bool operator<(MyClass&, MyClass&)
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Jul 31, 2013
I'm making a simple game and I'm having trouble creating boundaries for the players movements. The map is a 2D vector. When I compare the vector with the players current position sometimes I get an error during run. When the error isn't occurring the behavior of the boundaries is bizarre. The error tells me that the vector is out of range.
Here is the where the map is created. It's within its own class constructor.
vector< vector<char> > map_parts;
map_parts.resize(25);
for ( int i = 0; i < 25; i++ )
{
[Code].....
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Jul 28, 2014
I have this statement - while(strcmp(x[i],"Stop")!=0); - is there anyway to compare x[i] to all the possible forms of "stop" (Stop, STOP, sTop, etc)?
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Aug 28, 2014
I made a program that allows the user to enter information of credit cards on an array of size 5, however I need to allow the user to compare the five credit cards with each other and I am having problems with this particular part. I made my bool operator functions for the operator< and the operator> but how to make the user be able to select which cards he wants to compare and how to compare them. My code is the following:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int SIZE = 5;
enum OPCIONES {CARGAR=1, ABONAR, NADA};
[Code] ......
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Jul 14, 2014
This is some code that simulates files and directories the same way an operating system does so. I commented out every std::string occurrence because I got the :
terminate called after throwing an instance of 'std::length_error'
what(): basic_string::_S_create
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Jan 21, 2013
I just would like to turn this into cpp:
string eg("azertyFTW");
if(eg[one of the letters contained in this string] == 'c') {
cout << "eg has the letter c in it";
} else {
cout << "not this time :(";
}
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Jan 8, 2012
so i have a std::map like this:
map<DWORD,DWORD> mymap;
now i want to sort it by the second DWORD value, and thus i have to implement my own comparison function and use sort() from <alogirthm>:
Code:
bool y(const map<DWORD,DWORD>::iterator& a, const map<DWORD,DWORD>::iterator& b)
{
if(a->second < b->second)
return 1;
else
return 0;
}
...
sort(mymap.begin(), mymap.end(),y);
...
but this throws thousands of errors at me, including C2784.
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Mar 29, 2013
I have an assignment where I need to go through all the files in a folder. For each file I need to know each unique file extension, how many files for each unique file extension, and the total size for each unique file extension. I have to be able to sort through this using either the file extension or the total size of the file extension. The first thing I thought of using was a map. This will keep track of each unique file extension and the amount of times that file extension was found. How do I now associate the total size of the file extension to my map? So for example I need the output to be something like this:
Using file extension for sort
.cpp : 1 : 3400
.exe : 3 : 3455600
.mp4 : 25 : 200000404
Using total file extension size for sort
.mp4 : 25 : 200000404
.exe : 3 : 3455600
.cpp : 1 : 3400
Here is the code I have so far:
Code:
#include <iostream>
#include <filesystem>
#include <map>
[Code]...
I was thinking of somehow using a class to implement this, but don't know how to go about doing that. A
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Apr 27, 2013
bool simpleQuestion::checkAnswer(string guess) const {
for (int i=0;i<qAnswer.length();i++)
if (qAnswer==guess)
return true;
else
return false;
}
This is my code and what im trying to accomplish here is making the comparison of the two strings (qAnswer & guess) case insensitive. I know i need to loop through each character of each string and for each character i can use toupper and every char in each string will become uppercase and therefore case insensitive. However, im not sure how to go about this; if any technique used to loop through each character of the string and how to use to upper.
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Apr 21, 2013
I am trying to make a program that prints out an 8 by 8 board with 1 queen on each row.
For example, if the user enters: 0,3,4,0,0,7,6,7
the program should create following board and print:
Q.......
...Q....
....Q...
Q.......
Q.......
.......Q
......Q.
.......Q
I think I am doing it right but im getting a couple of errors that i cant fix ...
#include <iostream>
using namespace std;
int main(){
int x [8] [8], r, c;
for(c = 0; c <= 8; c++){
cout << " Enter a number from 1 to 7 " << endl;
[Code] .....
these are the errors :
assignment15_meem.cpp: In function âint main()â:
assignment15_meem.cpp:7: error: no match for âoperator>>â in âstd::cin >> x[c]â
assignment15_meem.cpp:10: error: ISO C++ forbids comparison between pointer and integer
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Jan 30, 2014
I am trying to count the number of comparisons for each of the following sorting algorithms, Selection, Insertion, Bubble, Merge, and Quick sort. This is using an array of numbers that are sorted, reversed, and randomly arranged.
I currently increment the "number of comparison" variable before every conditional statement that compares two numbers and am getting the following results:
Number of Items in Array = 100
Selection: random = 5049; reverse = 5049; sorted = 5049;
Insertion: random = 2640; reverse = 5049; sorted = 99;
Bubble: random = 9207; reverse = 9900; sorted = 99;
Merge: random = 1221; revere = 988; sorted = 1028;
Quick: random = 690; revere = 587; sorted = 636;
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May 4, 2014
template <class ST>
bool OrderedSet<ST>::IsIn (const ST & value) const {
for (LNode * np = first; np != NULL; np = np -> next)
if (np -> next == value)
return true;
return false;
}
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