小编drh*_*unn的帖子

我刚刚开始学习 Java 中的 Streams 和并行，我想知道为什么普通的 for 循环IntStream在向数组添加项时比并行花费的时间更少。

package parallel;

import java.util.stream.IntStream;

public class Parallel {

    public static void main(String[] args) {
         final int[] intArray = new int[100000];
        long startTime = System.currentTimeMillis(); 
        IntStream.range(0, 100000).parallel().forEach(i ->  intArray[i]=i);
        long endTime = System.currentTimeMillis();
        System.out.println("Parallel time: " + (endTime-startTime));
        final int[] intArray2 = new int[100000];
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        startTime = System.currentTimeMillis();
        for(int i = 0; i < 100000; i++){
            intArray2[i] = …

../NoteConverter.c: In function ‘main’:
../NoteConverter.c:154:9: warning: variable ‘position’ set but not used [-Wunused-but-set-variable]
Finished building: ../NoteConverter.c

Building target: NoteConverter
Invoking: GCC C Linker
gcc  -o "NoteConverter"  ./NoteConverter.o   
../NoteConverter.c:21: error: undefined reference to 'sin'
collect2: error: ld returned 1 exit status
make: *** [NoteConverter] Error 1

以下是代码

/**
 * Frequency octave finder and play note
 */

 #include <stdio.h>
 #include <string.h>
 #include <math.h>

 #define DURATION 5
 #define SAMPLERATE 48000
 #define AMPLITUDE 1

 //A*sin(2*pi*n*f/R)

double yCord(int n, double freq)
{
    double y= sin(2*M_PI*freq*n/48000); …

我不知道我在哪里出错了,任何帮助都会有所帮助.我试图用2个不同的字符串数组制作一副牌并将其打印到控制台.编译很好,但是当我运行它时,我得到"Segmentation fault(core dumped)"

/*
* BlackJack.c
*
*  Created on: Feb 25, 2014
*      Author: Danny Hunn
*      25 Feb 14 builds a deck for Black Jack
*/

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#define NUM_SUITS 4
#define DECK_SIZE 52
#define NUM_RANKS 13


void swap(char *first,char *second)// swapping pointers
{
char temp = *first;
*first = *second;
*second = temp;

}
void shuffle(char *deck[])
{
int seed, gen, i;
seed = (int) time(0);
srand(seed);

for(i =0; i < …