This is my semaphore, i want to improve this code with mutual exlusion:
semaphore(){
int cont;
mutex lock;
Condic condit();
down(){
lock.acquire();
[Code] .....
I found that one way is with TSL Test and set Lock, but i couldn't find the way to call it in C. Then i found the windows call enterCriticalRegion but it's not what i want.
I have a program that spawns a number of threads. Each thread generates a table of output. During the time that it is creating this output, I don't want the other threads to be outputting, so I've attempted to create a mutex semaphore to allow only one thread at time to ouput.
Code:
sem_t mutex;
void* node(void *thread_arg) {
// set a mutex lock to allow the output for this next step to complete for this thread
sem_wait(&mutex);
// generate table with various fprintf statements
}
[code]....
This approach isn't working.
So, say I have a process and its placed into the binary semaphore, I can't have the same process be placed into the same binary semaphore or any other binary semaphore right? Or can I?
View 1 Replies View RelatedI don't understand why my compiler gives me this error when I'm trying to run this code:
Code:
#include <iostream>
#include <cmath>
using namespace std;
class Airplane
{
public:
Airplane();
~Airplane();
[Code]...
The variable is protected. Yeah, that's right. But shouldn't a derived class be able to reach it? Or is it only in a function that the derived class is able to reach protected variables and isn't able to reach protected variables in the constructor?
I'm trying to blur a ppm image by averaging the components of the color(r, g, b) within a certain reach of a specific pixel. This is a picture and description:
In this diagram, we are trying to compute the color for the pixel in the center (the red element). Its neighbors (within a reach of 4) are all of the green elements. The pixels outside of this 9x9 square are not considered in the blurring calculation for this pixel. To compute the color for the center pixel, average the red, green, and blue components (independently) of every pixel in the 9x9 square (including the pixel itself; the red element in this diagram).
I have some code, but it is not working correctly. The function "computed_color" on line 52 is shown in the next block of code.
Code:
#include <stdlib.h>
#include <stdio.h>
#include "blur_calculations.h"
#define NOT_ENOUGH_ARGS 2
#define MIN_ARGS 3
#define PICTURE_FILE 1
#define REACH_NUMBER 4
#define OUTPUT_FILE "blurred.ppm"
#define PPM_NUMBER "P3"
#define MAX_ROWS 500
#define MAX_COLS 500
void solve(FILE *in_picture, FILE *out_picture, char *argv[]) {
[Code] ....
Here is my code to calculate the average, which I use in my "solve" function:
Code:
#include "blur_calculations.h"
struct color create_color(int r, int g, int b) {
struct color colors;
colors.r = r;
colors.g = g;
colors.b = b;
return colors;
[Code] ....
Linker error.
First off the error
Code:
Error1error LNK2019: unresolved external symbol "public: __thiscall ReachTop<class Character>::ReachTop<class Character>(class Character *)" (??0?$ReachTop@VCharacter@@@@QAE@PAVCharacter@@@Z) referenced in function "void __cdecl `dynamic initializer for 'gReachTop''(void)" (??__EgReachTop@@YAXXZ)Main.objDecisionTest
Reach Top class inherits from Goal Class
Goal Class
Code:
#ifndef _GOAL_H
#define _GOAL_H
#include "Action.h"
#include <list>
template <class T>
class Goal
[Code] ....
Code to create
Code:
Character* gCharacter = new Character(1, gWorld);
Goal<Character>* gReachTop = new ReachTop<Character>(gCharacter);
I can provide the character class and its inheritance aswell if you like.
So I have a template, part of a larger code, that is designed to calculate the number of multiplications it took to reach a certain number. The problem is, whenever I execute the program, mults is always printing out a strange number, perhaps its actual address.
template <class T>
T power3(T x, unsigned int n, unsigned int& mults) {
if (n == 0) return 1;
if (n == 1) return x;
if (n == 2){
[Code] ....
How do you store a map value inside a map?
Here's my code:
map<map<string, string>, int> Name;
I have a map which contains a multiset and another map
std::map<std::multiset<int>, std::map<int, int> >
And I need to sort the whole map according to the mapped value of the inside map, then output the data from the keys i.e. from the multiset and the first value of the inside map. I have tried to create a vector of pairs
std::vector<pair<std::map<:std::multiset<int>, std::map<int, int> >, int> >
and populate the first element with the map and where the second integer of the pair will be the mapped value to sort. I have tried iterating over the map to populate the vector but I'm not sure how to do so.
I would like to choose same case for multiple switch conditions.
For example:
Code: switch(choice) //''if choice ==0 or choice ==1, chose same case''
{
case (0 || 1):
{
//execute steps
}
break;
default:
{
//execute steps
}
break;
}
The '||' inside case does not have the desired effect (although it compiles fine). How can I do it without using if-else statements.
I keep on getting error message while trying to pass a function inside a for_each loop.. I have a vector and i used for_each loop to go through the rows in that vector, Now I need a function to do something
Example this is what I am trying to achieve
for_each (label.begin(), label.end(), addToTemporaryVector());
void DataPartitioning::addToTemporaryVector(){
cout<<"sucess";
}
But I get an error message saying: error: invalid use of void expression
I am working on a small game and I have the following problem. I need to get the colour of a particular position in an image. Say I'm given coordinates (5,5) I need the colour of the part in the image. I think I can do the colour picking myself, but I don't know how to point at coordinates inside the image.
View 3 Replies View Related[URL] ....
Can I make these squares appear around the other instead of having them appear under the others. Also if it can be done how can I make it so there is a space between the squares
int main() {
char a;
int size = 0;
cout << "Enter a character: " << endl;
cin >> a;
while (size < 1 || size > 10)
[Code] ....
So, I have created a class called "point" and i have 4 "point" objects. They only have 2 variables, x and y (their position). The first 3 points form a triangle and now I need to tell if the forth one is inside or outside. I have found some solutions but they involve heavy math (they are based on the sum of the angles or something like that). I want to know if there is any way to solve this only by using the distance between points. I have created a function which takes 2 "point" objects and returns a float value which is their distance.
Here is some code:
#include <iostream>
#include <cstdlib>
#include <math.h>
using namespace std;
[Code]....
I'm trying to create a simple calc program that does all the elementary calculations. How to get it to add and multiply continuously without crashing. but now i need to figure out how to ask the user if they want to continue or not. I'm having trouble here because in the while statement i have a scanf which asks for the operator symbol. and then asks for number in the second scanf..
So basically a user would have to enter 'R' twice for the message to pop up! Also i'm not sure how i would quite the program if they put in a 'N' for no. would return 0; work? What if they press 'Y' for yes, what would the return have to be then?
Here's a snippet of the code
int main () {
double result;
double new_number;
char symbol;
result = 0;
while(1==scanf(" %c", &symbol) && symbol == 'R' && symbol =='r')
[Code] .....
I am trying to write a basic editor program and one of the parts asks me to "process dot commands that move point in whole line increments"
Earlier it says that a point is interpreted as specifying the location between characters rather than the characters themselves. and i need to use this to implements the following:
< moves point to the beginning of the document. > moves point to the end of the document. p moves point to the beginning of the previous line. n moves point to the beginning of the next line. k deletes the current line and leaves point at the beginning of the following line.
(there was a previous part before this so i already have some code that works) and in this part I'm trying to do a switch case
ie
for
< , >, p , n and k
I guess my question is how do i make this "point" need. Ive been using vectors, so the point needs to be somewhere inside the vector. I don't think ill be able to do what i need to do with out the point.
while writing code i got a question. For example i created a class named as unit.
Think a simple game, and the unit class will belong the units.İf i give the preferences as private one by one, it will be irregular. For a detailed game; height, weight, race, hair preferences, eyes... Strength, dexterity, charisma, intelligence, wisdom, constution... experience, damage, armor...
and should i use struct to group them? And how to can i use struct at the inside of class as private?
Alright, so I have a code that's not giving me errors, but it doesn't seem to retain what I put into an array. Not sure If I'm missing something...
Code:
#include <stdio.h>
int main (void)
{
const char *pointer;
const char alphabet[] = "ABCDEFG";
pointer = &alphabet[5];
printf("pointing to %c of the alphabet
", pointer);
return 0;
}
Trying to get my pointer to return the letter in the [5] spot or "F". Not receiving any errors when compiling, but I seem to get different answers every time I run it.
I tried normal swapping method like this (counter is number of structures written in file) :
Code:
fopen("books.txt","r+");
system ("cls");
for(i=1;i<counter-1;i++){
for(j=1+1;j<counter;j++){
fscanf(f," %[^,], %[^,], %[^,],
[Code] ....
But it doesn't do anything.
Let me say I have a structure
Code:
struct time{
char hours;
char minutes;
char seconds;
char dummy;
};
I have kept dummy as the data to be aligned.I will update hours, minutes, and seconds , but will not use dummy in any case. If I don't initialize 'dummy' does it make any errors ? Do I need to initialize hours, minutes, seconds as well before I use the structure ? If so is there any particular reason ?
This has never happened before but I imagine that I've somehow accidently disabled a library or such.
namespace SB{
namespace Data{
class DLL Filed abstract{
//DLL is a macro defined as either __declspec(dllexport) or __declspec(dllimport)
//depending on whether this is open as a project or a header
[Code]....
The error is from intellisense and is present on every occurrence of std::string
Ive recently got into function pointers, i find that they can be quite handy for making your program very 'dynamic'.
However, the syntax is very confusing for what i want to do
This is what i want to do
I want to hold function pointers inside an array, but this array is dynamically allocated ( malloc, realloc, etc )
This is the current syntax ive come up with, but i dont think it is correct
void ( **drawFunc ) ( void*, SDL_Surface* );
class Hallway {
private:
//---------------------------------------------------------------
// DO_04: Declare a Light array of size MAX_LIGHTS
// Hint: look through the methods below to find the name to use
// for the array
//---------------------------------------------------------------
int numLights;
int lights[MAX_LIGHTS];
[Code] .....
I keep getting the error " this.lights[i] is not a struct or class and so you cannot use '.' " on line 34.
How am I supposed to define my lights[] array? I can't modify anything except directly after each comment block.
I have one array with size of 5 and passing this array to one method. I want to get size of the array inside method. If i get size of array inside method, i'm getting only "1",but not "5".
int v[5];
v[0]=1;
v[1]=2;
v[2]=3;
v[3]=4;
v[4]=5;
cout<<sizeof(v)/sizeof(&v[0])<<endl; // here i'm getting size as 5
CreateArray(v);
void CreateArray(int val[])
{
cout<<sizeof(val)/sizeof(&val[0])<<endl; // here i'm getting size as 1
}
Is there any way to get size inside method ?
I have a problem with pointer array, i passed a 2d array to a function but then i dont know how to make operations on it !!!
#include <iostream>
using namespace std;
int fun_name (int * arr) {
for (int i = 0;i< ??? ;i++) // how to compare while i don't know the size of array!!
[Code] ....
So I'm trying to delete a value stored inside one of my vectors but I can't accomplish this. My attempts are down below. I've commented out one attempt since it gives me errors. How can I do what I am trying to do?
#include <iostream>
#include <vector>
using namespace std;
int main() {
vector<vector<int> >row;
vector<int> newColumn;
[Code] ....