随机数产生 M-N

#include <iostream>#include <ctime>#include <cstdlib>using namespace std;int main(){    double random(double,double);    srand(unsigned(time(0)));int a;FILE *fp;char ch[10]={0};fp=fopen("rand1212.txt","a+");    for(int icnt = 0; icnt != 100; ++icnt){a=int(random(10,20));sprintf(ch,"%d\r\n",a);fputs(ch,fp);        cout << "No." << icnt+1 << ": " << a<< endl;}fclose(fp);    return 0;}double random(double start, double end){    return start+(end-start)*rand()/(RAND_MAX + 1.0);}