C++ :: Getpixel Function (SDL Documentation) Color Comparison
Nov 6, 2013
I think that the getpixel function (existed in sdl documentation) gets the color of the coordinate indicated by x and y
Uint32 getpixel(SDL_Surface *surface, int x, int y) {
int bpp = surface->format->BytesPerPixel;
/* Here p is the address to the pixel we want to retrieve */
Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
switch(bpp) {
[Code]...
my problem is that, I want to compare it with the white/black color ,so how can I do that?
I tried this way but it does not work
int main(int argc,char *argv[]) {
SDL_Init(SDL_INIT_VIDEO);
SDL_Surface *screen = SDL_SetVideoMode(600,400,32,SDL_HWSURFACE|SDL_DOUBLEBUF);
SDL_Event event;
bool pass = true;
SDL_Color color = {0,0,0};/// Black color
if(color==getpixel(screen,0,0)
[Code]...
the error C:Documents and SettingsTechno01Bureausdlmain.cpp|83|error: no match for 'operator==' in 'color == getpixel(screen, 0, 0)'|
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Nov 23, 2013
I would like to see what functions the following header file has:
#include <tf/LinearMath/Transform.h>
Any website that has all the c++ libraries and where to find the functions that come with this?
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Jun 4, 2013
I'm building a simple little program for minecraft to reduce the repetitiveness, I'm using getpixel, it's slow, but i only need to grab about 6-12 pixels.
but the problem is, I can get the pixel data if I capture from the entire desktop display, but as soon as I tell it to grab from the active window (wich goes MUCH faster) it doesn't return any colour value's.
I'd rather not have to use getDIBits or program in java or anything since I want to keep it fairly kiss, and if it can't be done, then.. ah well, I'll just grab from the entire desktop, speed isn't to much of an issue, but it'll be a pain to keep the window at the same place.
Code:
#include <Windows.h>
#include <iostream>
using namespace std;
// vvv Ignore this, it's just used for retrieving the handle of a window without giving the full window name vvvv
struct results {
[Code] ....
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Jan 27, 2012
Why I'm getting an error here. I've dumbed down my code for simplicity and removed irrelevant code.
PHP Code:
class Foo {
public:
bool IsNull() const;
private:
std::map<int, int*> test;
[Code] ....
I'm getting a "passing...discards qualifiers" error on my if statement and not sure why because I'm not changing anything. I know removing const or making test mutable fixes the issue. I've been taught to always make a function const if it doesn't change anything, in which case, have I finally come across an acceptable time to use mutable?
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May 5, 2014
I'm trying to write a function called 'set' that sets the value of the i'th cell to val on my linkedList, and then returns the previous contents. I am stuck on it due to compiling errors:
This is my Node struct:
#ifndef NODE_H
#define NODE_H
#include <iostream>
template <typename T>
struct Node {
friend std::ostream &operator <<(std::ostream &os, const Node<T> &node) {
[Code] ....
The following is my set function:
template <typename T>
T set(Node<T> *head, int i, const T &val) {
for(int n = 0; n < i; n++)
if(head == val) {
val = i;
} return val;
} #endif
When I try to call it in the main() I get these errors:
node_utils.h: In function ‘T set(Node<T>*, int, const T&) [with T = int]’:
node_demo.cpp:26:38: instantiated from here
node_utils.h:161:2: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
node_utils.h:162:3: error: assignment of read-only reference ‘val’
So, I understand that I can't compare head & val on my if-statement -- But what do I do?
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Sep 7, 2014
Trying to define some global colors so I can use the one instance though-out my application. Here is my color code:
<Color x:Key="GlobalTextColor">#E0E0E0</Color>
But this color doesn't display in the list when I start to type {StaticResource ...}
This is the code where I'm trying to reference the color, see Stroke="{StaticResource GlobalTextColor}". GlobalTextColor doesn't actually come up in the list so won't work.
<Style x:Key="InputButton" TargetType="Button">
<Setter Property="Background" Value="#FF141414" />
<Setter Property="HorizontalAlignment" Value="Left" />
[Code].....
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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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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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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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Feb 10, 2013
How to compare two files(two texts documents) and display their similarity percentage by using C++?
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Sep 15, 2014
how to put comparision condition in order to caculate total number of comparision in selection sort
static void selectsort(int[] data, int n)
{
int i, j;
for (i = 0; i < n; i++)
[Code]....
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Feb 20, 2014
So I have started this program for class but am stuck on what to do next. Basically you need to create a function to compare 2 strings (case-insensitive). The strings shouldn't be altered and the return value should be similar to strcmp.
This is my main file
#include <iostream>
//#include <cstring>
#include <iomanip>
#include "rpstrings.h"
using namespace std;
int main () {
char Str1[20], Str2[20];
short result;
[Code] .....
I don't know if I labeled the files correct. what I need to do is to add 2 defaulted arguments which will allow the user to request that you skip spaces and/or skip punctuation when doing the comparison.
Also, how I can sort the numbers when they aren't justified with leading 0's and if they aren't in the lead string (kinda of like the natural sort).
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Nov 7, 2013
So I have an insertion sort function implemented that sorts through an array, but I'm having a problem showing the correct number of comparisons to work.
Each time I'm checking a value with another, the counter should update.
For instance, having an array of 10 elements going from 10-1 should give 45 comparisons, but I'm getting 54 comparisons.
void insertionSort(int a[], int& comparisons, const int& numOfElements) {
int j, value;
for (int i = 1; i < numOfElements; i++) {
value = a[i];
for (j = i - 1; j >= 0 && a[j] > value; j--)
[Code] .....
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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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Feb 16, 2013
Code:
do {
printf("Edit the entry's cellphone number:");
scanf("%s", addressbook[4][num]);
length = strlen(addressbook[4][num]); //gets the length of the input (should be 10)
//checks if the input is composed of 11 elements wherein the first 2 are 0 and 9 respectively
for(i=0; i<11; i++){
[Code] ....
why do I get an error here?
Code:
if ((addressbook[4][num][0] == '0') && (addressbook[4][num][1] == '9') || (addressbook[4][num][i]>='0') && (addressbook[4][num][i]<='9') && (length=='11'))
And how do I fix this?
The error message is: comparison is always false due to limited data type
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