C++生成随机数

 1 #include <iostream>
 2 #include <fstream>
 3 #include <cstdlib>
 4 #include <ctime>
 5 using namespace std;
 6 #define NUMBER 100000
 7 #define RANGE  1000
 8 
 9 int main(void)
10 {
11     ofstream fout;
12     int x;
13     int i;
14 
15     fout.open("random_number.txt");
16     if(!fout){
17         cerr<<"Can not open file ‘random_number.txt‘ "<<endl;
18         return -1;
19     }
20 
21     time_t start, end;
22 
23     srand((unsigned)time(NULL));      //生成随机数种子
24 
25     start=clock();
26 
27     for(i=0; i<NUMBER; i++){
28         x= rand() % RANGE;            //随机生成1000以内的随机数
29         fout<<x<<endl;
30     }
31 
32     fout.close();
33 
34     end=clock();
35 
36     cout<<"Successful Generation of Random Sequences!"<<endl;
37 
38     cout<<"Time : "<<end-start<<endl;
39 
40     return 0;
41 }