随机数

rand() 随机数发生器

#include <stdio.h>
#include <unistd.h>
#include <iostream>
#include <string>

using namespace std;

int main(int argc, char *argv[])
{
	cout << "this is main()" << endl;

	cout << rand() << endl;
	return 0;
}

控制随机数范围

[a,b)：使用 (rand() % (b-a)) + a
[a,b]：使用 (rand() % (b-a+1)) + a
(a,b]：使用 (rand() % (b-a)) + a + 1

#include <stdio.h>
#include <unistd.h>
#include <iostream>
#include <string>

using namespace std;

int getRand(int min, int max)
{
	return ((rand() % (max-min+1)) + min);
}

int main(int argc, char *argv[])
{
	cout << "this is main()" << endl;
	cout << getRand(0, 10) << endl;
	return 0;
}

srand() 设置随机数种子

#include <stdio.h>
#include <unistd.h>
#include <iostream>
#include <string>

using namespace std;

int getRand(int min, int max)
{
	return ((rand() % (max-min+1)) + min);
}

int main(int argc, char *argv[])
{
	cout << "this is main()" << endl;

	srand(time(NULL));
	cout << getRand(0, 10) << endl;
	return 0;
}