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Re: Some Problems about gcc 4.8.2 on cygwin




On 14/03/2014 13:42, rexdf Rexdf wrote:
1.the following code:

#include <unistd.h>
#include <curses.h>
int main() {
    initscr();
    move(0, 0);
    addstr("hello, world\n");
    refresh();
    sleep(5);
    endwin();
    return 0;
}

The following is my shell command:

$ pkg-config --libs --cflags ncurses
-I/usr/include/ncurses  -lncurses

$ gcc $(pkg-config --libs --cflags ncurses) curses_test.c -o curses_test

try this way

gcc  curses_test.c -o curses_test $(pkg-config --libs --cflags ncurses)


2.It's about OpenMP
openmp_1.cpp
#include <iostream>
#include <time.h>
void test()
{
     int a = 0;
     for (int i=0;i<100000000;i++)
         a++;
}
int main()
{
     clock_t t1 = clock();
     for (int i=0;i<8;i++)
         test();
     clock_t t2 = clock();
     std::cout<<"time: "<<t2-t1<<std::endl;
}

openmp_2.cpp
#include <iostream>
#include <time.h>
void test()
{
     int a = 0;
     for (int i=0;i<100000000;i++)
         a++;
}
int main()
{
     clock_t t1 = clock();
     #pragma omp parallel for
     for (int i=0;i<8;i++)
         test();
     clock_t t2 = clock();
     std::cout<<"time: "<<t2-t1<<std::endl;
}

On cygwin
g++ openmp_1.cpp -o openmp_1.exe
g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
time 1937
time 2297

On MingW-g++ 4.8.1
g++ openmp_1.cpp -o openmp_1.exe
g++ openmp_2.cpp -o opemnp_2.exe -fopenmp
time 1975
time 492

On Visual Studio 2013
Openmp_2.cpp Project
C/C++ --> Language --> Open MP Support yes(/openmp)
time 1849
time 321

and the question is ?

Marco

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