C random number, random number

C random number, random number

 

This is a bit of a pitfall. The results are the same every time, so good random is not random. In fact, the random number itself is also calculated, and each time it is calculated by the random number seed. If the random number seed is different, the calculated random number is different, and the function that generates the random number seed is also in stdlib. h. The function is srand ().

[This part of code is in function1]

We need to give random number seeds different values each time, and then we can get different random numbers, but there is another drawback. How can a seed get different values. We know that time is different all the time, so if we can use time to give the random number seed, the results will be different each time.

Get

 

The result is better.

 

The following source code.

 

 

# Include <iostream> # include <stdlib. h> # include <time. h>/** rand () from stdlib. h file */void function1 (void); void function2 (void); // int [] makeArray (int array []); // how to return an array of the int type? Void display (int array []); int main () {function1 (); function2 (); return 0;} void function2 (void) {int array [10]; int randomseed = (int) time (NULL); // contained in time. in h, // return the current time. The time type must be forcibly converted to the int type. Srand (randomseed); for (int I = 0; I <10; I ++) {array [I] = rand () ;}display (array );} void function1 (void) {// we use rand () to generate a random number: int array [10]; for (int I = 0; I <10; I ++) {array [I] = rand ();} display (array);} void display (int array []) {for (int I = 0; I <10; I ++) {printf ("array [I] = % d", array [I]); if (I + 1) % 5 = 0) {printf ("\ n ");}}}