C++ :: OpenMP - Intervals Assigned To Threads?
Feb 6, 2014Is there a way of knowing which indices a thread is assigned in a parallel openMP scope?
View 6 Replies
ADVERTISEMENT
C :: Subtract Two Time Intervals?
Mar 12, 2014I am looking for simple code that subtract two time interval. I have time t1=5hour 30 minute and other time in 24 hour format. This code i written but it not working as expected. it not printing 5:30 minute subtract
Code:
main() {
intTime1;
intTime2;
int hour=10;
int minute=5;
int second=13;
int h;int m;
doubleNtime;
[Code] ....
C/C++ :: Subtraction - Two Time Intervals
Mar 12, 2014I am looking for simple code that subtract two time interval. I have time t1=5hour 30 minute and other time in 24 hour format. This code i written but it not working as expected
main() {
intTime1;
intTime2;
int hour=10;
int minute=5;
int second=13;
int h;int m;
[Code] ....
Is there any easy way of doing above code. Above two code section not working....
C :: Printing Current TIME At Regular Intervals
Aug 22, 2013Its a code in module of my program, where I need to print current time (HH:MM:SS) at regular intervals.
Code:
#include<time.h>
#include<stdio.h>
//#include<windows.h>
void delay(unsigned int t){ // loop for some delay.
[Code] ....
But when I am running this code I expect this to print difference in time due to delay. But it doesn't enter the delay loop, why ?
C++ :: Getting Multiple Objects To Move Randomly At A Designated Number Of Intervals
Jan 9, 2015I have a piece of code which gets multiple objects to move randomly at a designated number of intervals. I want to create a function which calculates the distance between each pair of points after that number of steps. so the distance between object 1 and object 2, object 1 and object 3, ..., object 1 and object N. then object 2 and object 3, object 2 and object 4, ..., object 2 and object N. then then object 3 and object 4, object 3 and object 5, ..., object 3 and object N and so on until the distance between all the pairs of points have been calculated.
#include <ctime>
#include <cstdlib>
#include<iostream>
#include<cmath>
#include<iomanip>
#include<fstream>
#include<vector>
using namespace std;
double dist(int a, int b);
int X(int x1, int x2);
int Y(int y1, int y1);
[Code] ....
C :: Threading With OpenMP
Apr 10, 2013I wrote code that finds the number of prime numbers in a range entered by the user. Now I'm attempting to make it run in parallel with the number of threads I assign it to have. I'm using blocking technique, so I'm assigning, in this scenario, 4 threads - 1/4 of the numbers in the range to the first array, and the next 1/4 of the numbers in the range to the next array and so on. Then I want to execute the prime number counting code in parallel. I'm using openMP to do this. I'm having difficulty setting it all up properly. I have a little experience with pthreads but little with openMP and am struggling in how this should be done.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <omp.h>
[Code]....
C/C++ :: Getting Error While Using OpenMP Along With Map
Dec 19, 2012I am using map for assigning an identifiers for a line from file in c++. Also i am using IDs for a pattern in line {name, operator, val} which is separated by ';'. I am using read_pub() for calculating how many patterns are there in a line.
#include<stdio.h>
#include<stdlib.h>
#include<iostream>
#include<fstream>
#include<omp.h>
#include<map>
#include <sstream>
using namespace std;
struct predicate {
[Code] ....
C :: Translate Pthreads Into OpenMP
May 20, 2013I'm quite new to openMP, mostly used pthreads and mpi before. Now I like to tinker a bit with openMP, but haven't found any good docs, reference list or similar.
What's the equivalent to pthread's mutex lock in openMP?
Code:
#pragma omp parallel for
for(i=0; i<n ; i++){
// Do something intelligent...
// If needed handle a shared variable.
}
How do I protect the shared variable?
C :: Using Counter Variable With OpenMP
Oct 14, 2014I'm trying to write a small brute force application in C on Ubuntu 14.04.1 using Code::Blocks with gcc-4.8.2. It's nothing special and just for practice.The focus is on a parallel procedure that generates strings by use of OpenMP. Every time a string is generated, the counter variable should be incremented. At the end, regardless of whether the search string was matched or not, it outputs the correct number of all generated strings (counts).It works fine so far.Here is my source code example:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <omp.h>
/* Global variables */
const char Literals[] = "abcdefghijklmnopqrstuvwxyz";
const int NLiterals = sizeof( Literals ) - 1; // NLiterals = 26 Bytes.
const char SearchString[] = "test"; // I.e. until 'test' there are 355414 counts.
char MatchString[16];
}
[code]...
This should speed up the process of generating strings. But if I do so, always when the program has a match the number of counted strings is wrong. Here are some possible "wrong" outputs: Code: Match: 'test'! 40710 tries. <-- number of tries (counts) is wrong! or Code: Match: 'test'! 40375 tries. <-- number of tries (counts) is wrong! But if the program doesn't have a match (i.e. when I change SearchString to something like the following line), then the number of counts is correct: Code: const char SearchString[] = "test0"; The only thing I have to do before, is to change the follow line from:
Code:
printf( "
No match! %u tries.
", Count / 8 ); to Code: printf( "
No match! %u tries.
", Count );
But also it can happen that there is no output. Like an infinite or endless loop. How can I improve the source code in order that the correct number of counts is always displayed and what can be the reason for the endless loops time after time? Both issues appears only by the use of Code: #pragma omp for schedule( dynamic ).
C++ :: OpenMP Parallel Is Not Working
May 22, 2013I'm trying to implement Parallel loop with OpenMP. I just googled and got the below sample, but it seems its not executing parallely. It takes same amount time for code which is with parallel and without parallel.
Without Parallel : It takes 39 secs.
-----------------
for (int I=0;I<100000;I++){
cout<<I<<" ";
}
With Parallel : It takes 39 secs.
--------------
#include<omp.h>
#pragma omp parallel {
#pragma omp for
for (int I=0;I<100000;I++) {
cout<<I<<endl;
}
}
Why parallel is not working and it takes same time. My machine is Dual Core.
C++ :: Value Assigned To Int Variables?
Feb 6, 2013Suppose x, y, and z are int variables. What value is assigned to each of these variables after the last statement executes?
x = 4; y = 11;
z = y - 2 * x;
x = z + y;
y = x + 5 * z;
w = x - y + 2 * z;
x = y + w - x;
-w;
C++ :: Using One (dedicated) Vector Per Thread (OpenMP)
Apr 11, 2013I recently picked up multithreading with OpenMP, so it is still new to me. While processing data, I would like to store it in a vector, as shown here:
vector<int> vect;
#pragma omp parallel for
for(int c=0; c<500; ++c) {
vect.push_back(c)
}
However, since it is multithreaded, I would like (and need!) to have one dedicated vector per thread. I haven't been able to find an example of how to do this online. Is it even possible?
C/C++ :: OpenMP Can Make For Loop Faster?
Dec 9, 2014I'm trying to optimize this code using openMP. The line I added made it run about twice as fast but I'm trying to figure out how to make it even faster. Could reshaping the loops potentially increase the speed?
//4 threads
int listsize=15000;
#pragma omp parallel for shared(f) private(i,j,hash)
for(i = 0; i < listsize; i++) {
printf("Thread: %d i: %zu wl_size: %zu
",omp_get_thread_num(),i,wl_size);
for (j = 0; j < num; j++) {
h = f[j] (getw(list, i));
c[h] = 1;
} }
C :: Parse Error / What Value Does Get Assigned
Dec 10, 2013I get the following parsing error for the code
Code:
#include <stdio.h>
int main()
{
int i=3,4;
printf("%d",i);
return 0;
}
what is wrong with the code? I have put initialize value as 3,4 just to understand what value does i gets assigned.
C++ :: Does Int Vars Automatically Get Assigned (0)
Feb 13, 2015I am wondering if integers and unsigned integers automatically assigned to zero (0) upon declaration like so:
bool randomFunction() {
int i;
if (i == 0) {
return true; //Will most modern compilers return true here?
} else {
return false;
}
}
I am just curious as I have always initialized my ints/unsigned ints variables. Would save me a lot of typing if I didn't have to do this all of the time.
I know that floats and doubles you still have to initialize.
C++ :: Variable Assigned Wrong Value?
Nov 15, 2012Consider the following:
Code:
float foo( float const *bar )
)
{
float temp;
temp = *bar;
...
}
Something I am noticing is that temp right after the assignment to *bar, is not the same value as *bar. This is for a project at work and the code runs on an embedded board with an ARM processor. I've copied the function into a standalone program for both Visual Studio and Code::Blocks and it works correctly there.
C++ :: Getchar - Return Assigned Value
Nov 9, 2012Once again i hit a very simple problem i am unable to resolve. I using Visual Studio 2010, but am compiling for C.
This:
Code:
char i=45;
while(i=getchar() != EOF)
{
should imo work perfectly (yes, no real code, just to demonstrate the issue), but it doesnt. Getchar() always returns 0x01. Why is that? This, in contrast, works perfectly fine:
Code:
char i=45;
while(i!= EOF)
{
i=getchar();
Shouldnt an assignment always return the assigned value?
C :: GSL And OpenMP - Getting Random Numbers That Are Out Of Expected Range
May 2, 2013I am trying to parallelize some of my code with OpenMP. When I switch to using multiple threads I start getting random numbers that are out of the expected range.
Here is a small example:
Code:
#include <stdio.h>
#include </usr/local/include/gsl/gsl_rng.h>
#include </usr/local/include/gsl/gsl_randist.h>
int main() {
int mySeed=0;
const gsl_rng_type *T;
T = gsl_rng_ranlxs2;
gsl_rng *r_1 ;
[Code] .....
gsl_rng_uniform should only output number in the range [0,1) but with multiple threads it outputs larger number as well.
C++ :: Value Assigned To Variables X And Y Via Cin - Undeclared Identifier
Aug 28, 2012I've assigned value to variables x and y via cin, but when I try to compile it, I'm getting:
"1>c:users
isedocumentsvisual studio 2010projects ryityourself ryityourself ryityourself.cpp(26): error C2065: 'x' : undeclared identifier
1>c:users
[Code] .....
Code:
#include "stdafx.h"
#include <iostream>
void enterfirst() {
using namespace std;
int x;
[Code] .....
C/C++ :: Passing Var Assigned In A Class File To Functions Outside Of Int Main?
Dec 7, 2014I'm trying to pass the value of an object created from a class file to a function outside of the "Int Main" function in the main.cpp file. I've successfully created the object, I just want to pass it to a void function but I'm getting the scope error below. I'm not sure how to correct. I'm not having much luck with research either (static variables?).
error: 'TicTacToe' was not declared in this scope
main.cpp
#include <iostream>
#include <cstdlib>
#include "Signature.h"
#include "Gameplay.h"
using namespace std;
// Initialize array
char square[10] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
[code]....
Visual C++ :: Access Violation Reading Void Assigned Dynamically Allocated Value Inside Function
Sep 16, 2013Why the void pointer passed to testb doesn't continue pointing to the allocated integer after the function call returns.
Code:
#include <stdio.h>
#include <iostream>
void* testa() {
return new int(1);
[Code] ....
C :: Use SIGNALS To Control Threads
Nov 11, 2013I've to use SIGNALS to control threads. Here's my code without the use of signals as I'm no good at that
Code:
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
}
[code]....
C++ :: threads To Take Sequential Turns
Jun 30, 2014#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
int turn = 1;
int counter = 0;
int t, n;
[Code] ....
I found this program in a forum and it creates 1 to t threads with each thread pointing to the next and the last thread pointing to the first thread and it allows each thread to sequentially take a turn until all threads have taken n turns. That is when the program ends.
My doubt is if we see in void *tFunc(void *arg) function, first thread locks the mutex and then wait there forever till it's turn comes.Lets say if I spwan 1000 threads and they have take 10 turns each sequentially and what if a 550th thread locks the mutex as soon as the program starts and waiting for its turn which will never happen because still (turn=1) which means it's first thread's turn and first 549 threads have to complete their 1st turn before this 550 threda's turn comes.Doesnt this result in deadlock?
C++ :: Encapsulate Two Threads In A Class?
Apr 29, 2014how to encapsulate two threads in a class?
View 1 Replies View RelatedC++ :: Stopping Threads Without Using Local Var?
Aug 31, 2014Here's my code,
#include <iostream>
#include <unistd.h>
#include <thread>
using namespace std;
void Blink();
[Code] .....
The problem is i don't want to use local vars , is ther anyway do end the loop safely(removing all the vars used in function and etc) without using a local var ?
C/C++ :: Suspending And Resuming Threads
Apr 18, 2014#include <stdio.h>
#include <pthread.h>
int i; // loop control variable
int *id; // array used to pass parameter of id
int nThreads; // #threads
[Code]....
I want to know where I am going wrong. I am strong in java but not in c so that may be my problem.