功能
用到的觀念
CODE
#include"iostream"//標頭檔
#include"iomanip"
#include"cmath"
using namespace std;
using std::setw;
using std::fixed;
using std::setprecision;
int _tmain(int argc, _TCHAR* argv[])
{
int count=0;
unsigned long n,k,i,j,l,prime,temp=3;//n save the number of the end,
int m=0;//if m=1 i isn't a prime number. if m=2 i is a prime number
cout<<"find the number form 1 to n"<<endl;//顯示內容
cin>>n;//輸入存到n
system("cls");//clean the screen
cout<<"the prime number are:"<<endl;//顯示內容
if(n>2)//check whether n is bigger than 2
{
for(i=3; i<=n;i++)//從3檢查到n判斷是否為質數
{
for(j=2;j*j<=i;j++)
{
if(i%j==0)//if i is divided with no remainder
{
m=1;//save 1 to m
break;//jump from this loop
}
else if(i%j!=0)//i is divided with remainder
{
m=2;
prime=i;
}
}
if(m==2)
{
if((prime-temp)==2)
{
cout<<"("<<temp<<","<<prime<<")"<<endl;//show the content
count=count+1;//counter plus 1
}
temp=prime;
}
}
}
cout<< "there are " << count << " twin number"<<endl;//輸出值數的數量
system("pause");
return 0;
}
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