Use the js Math. random () function to generate random numbers between n and m.

Use the js Math. random () function to generate random numbers between n and m.

Abstract:

This article explains how to use js to generate random numbers between n and m. The main purpose is to prepare for later JavaScript code generation.

The Math. random () function returns a pseudo-random number between 0 and 1, which may be 0, but always less than 1)

Generate n-m, which contains n but does not contain an integer of m:

The first step is to calculate the m-n value, assuming that it is equal to w

Step 2 Math. random () * w

Step 3 Math. random () * w + n

Step 4 parseInt (Math. random () * w + n, 10)

Generate n-m, which does not contain n but contains an integer of m:

The first step is to calculate the m-n value, assuming that it is equal to w

Step 2 Math. random () * w

Step 3 Math. random () * w + n

Step 4 Math. floor (Math. random () * w + n) + 1

Generate n-m, excluding Integers of n and m:

The first step is to calculate the value of the m-n-2, assuming that it is equal to w

Step 2 Math. random () * w

Step 3 Math. random () * w + n + 1

Step 4 Math. round (Math. random () * w + n + 1) or Math. ceil (Math. random () * w + n + 1)

Generate a random number of n-m, including n and m:

The first step is to calculate the m-n value, assuming that it is equal to w

Step 2 Math. random () * w

Step 3 Math. random () * w + n

Step 4 Math. round (Math. random () * w + n) or Math. ceil (Math. random () * w + n)

Example:

Generate a random integer of 800 to 1500, including, but not

Copy codeThe Code is as follows:
1500-800 = 700
Math. random () * 700
Var num = Math. random () * 700 + 800;
Num = parseInt (num, 10 );

Only four simple steps are required.

Supplement:

Math. ceil () returns the smallest integer greater than or equal to the number parameter (take the entire function), rounded up the number

Math. floor () returns the largest integer smaller than or equal to the number parameter, and homes the number

Math. round () returns the nearest integer to the number, rounding

How can I use the C function to generate a pseudo-random number between m and n?

An example is available on msdn.
# Include <stdlib. h>
# Include <stdio. h>
# Include <time. h>

Void SimpleRandDemo (int n) // It is easy to generate n random numbers.
{
// Print n random numbers.
Int I;
For (I = 0; I <n; I ++)
Printf ("% 6d \ n", rand ());
}

Void RangedRandDemo (int range_min, int range_max, int n) // generate n random numbers between range_min and range_max
{
// Generate random numbers in the half-closed interval
// [Range_min, range_max). In other words,
// Range_min <= random number <range_max
Int I;
For (I = 0; I <n; I ++)
{
Int u = (double) rand ()/(RAND_MAX + 1) * (range_max-range_min)
+ Range_min;
Printf ("% 6d \ n", u );
}
}

Int main (void)
{
// Seed the random-number generator with the current time so that
// The numbers will be different every time we run.
Srand (unsigned) time (NULL ));

SimpleRandDemo (10 );
Printf ("\ n ");
RangedRandDemo (-100,100, 10 );
}

Use the random method of the math object to generate a random value of 100 ~ A random integer between 999 and more than 10 digits in Javascript

Function random_num (){
Var num = Math. random () * 999;
If (num <100 ){

Random_num ();

} Else {
Return num; // Random Number

}

}

Var _ num = random_num ();
Var shortwei = _ num % 100; // 10
Var shiwei = (_ num-baiwei) % 10; // hundreds of digits