使用 C++ 的 1 到 10 之间的随机数
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/12580820/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Random number between 1 to 10 using C++
提问by rajat
This code is supposed to generate random number between 1 to 10, but it returns 1 every time.
此代码应该生成 1 到 10 之间的随机数，但每次都返回 1。
int random_integer;
int lowest=1, highest=10;
int range=(highest-lowest)+1;
random_integer = lowest + int(range*rand()/(RAND_MAX + 1.0));
cout << random_integer << endl;
What's wrong in the code?
代码有什么问题？
回答by Luchian Grigore
You're subject to overflow here - range*rand().
您在这里可能会溢出 - range*rand()。
Just use what regular folks use: rand() % 10 + 1.
只需使用普通人使用的东西：rand() % 10 + 1.
回答by Fred Foo
range * rand() / (RAND_MAX + 1.0)
does not do what you think. Introduce some parens:
不做你想的。介绍一些括号：
range * (rand() / (RAND_MAX + 1.0))
(Note that this method gives skewed distributions, though.)
（但请注意，此方法会产生偏态分布。）
回答by Anton Guryanov
If you want a random integer between lowestand highest, you'd better write
如果你想要一个lowest和之间的随机整数highest，你最好写
random_integer = lowest + rand() % range
回答by birubisht
I agree with all the solution provided above .
now to get a different sequence every time you run your program you can use srand()function it will provide a seed to rand()function as follows:-
我同意上面提供的所有解决方案。
现在要在每次运行程序时获得不同的序列，您可以使用srand()函数，它将为rand()函数提供一个种子， 如下所示：-
srand(time(NULL))
random_integer = lowest + rand() % range
回答by SteveL
This two are always part of my programs
这两个永远是我程序的一部分
float randf(float lo, float hi) {
float random = ((float) rand()) / (float) RAND_MAX;
float diff = hi - lo;
float r = random * diff;
return lo + r;
}
int randi(int lo, int hi)
{
int n = hi - lo + 1;
int i = rand() % n;
if (i < 0) i = -i;
return lo + i;
}
回答by Sebastian Mach
You seem to assume that rand()returns a value between 0 and 1.
您似乎假设rand()返回一个介于 0 和 1 之间的值。
This is not correct, it return value between 0 and RAND_MAX.
这是不正确的，它返回 0 到 之间的值RAND_MAX。
