Re: [研究] short int

[yellowfishie (喵喵喵喵~~~)]

: 推 Donnie:感覺 short 計算比較慢                                    11/02 01:52
: → Donnie:除非要省記憶體，不然不會用 short                         11/02 01:52

實驗結果: short int 真的比較慢 = =

short int return function
[yellowfish@edasolaris c]$ g++ -O2 shortint.cpp; time ./a.out

real    0m7.552s
user    0m7.200s
sys     0m0.000s

int return function
[yellowfish@edasolaris c]$ g++ -O2 shortint.cpp; time ./a.out

real    0m5.462s
user    0m5.390s
sys     0m0.010s


測試程式:

#include <iostream>

#define SHORTINT 0

using namespace std;

#if SHORTINT
short int add1(int a, int b)
{
    short int c = a + b;
    return c;
}
#else
int add2(int a, int b)
{
    int c = a + b;
    return c;
}
#endif


int main()
{
    int a, b;
#if SHORTINT
    short int c;
#else
    int c;
#endif

    a = 2;
    b = 4;
    for (unsigned int i = 0; i < INT_MAX; i++)
    {
#if SHORTINT
    c = add1(a,b);
#else
    c = add2(a,b);
#endif
    }

    return 0;
}


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