srand
https://yongqiang.blog.csdn.net/article/details/104429546
Defined in header - 定义于头文件
srand
void srand (unsigned int seed);
Initialize random number generator - 初始化伪随机数生成器 (函数)
2. Example 2.1srand
//============================================================================
// Name : srand
// Author : Yongqiang Cheng
// Version : Version 1.0.0
// Copyright : Copyright (c) 2019 Yongqiang Cheng
// Description : Hello World in C++, Ansi-style
//============================================================================
#include
#include
#include
int main(void)
{
int random_variable = 0;
srand(time(0)); // use current time as seed for random generator
random_variable = rand();
printf("Random value on [0,%d]: %d\n", RAND_MAX, random_variable);
return 0;
}
Possible output:
Random value on [0,2147483647]: 1345030193
2.2 srand
//============================================================================
// Name : srand
// Author : Yongqiang Cheng
// Version : Version 1.0.0
// Copyright : Copyright (c) 2019 Yongqiang Cheng
// Description : Hello World in C++, Ansi-style
//============================================================================
#include /* printf, NULL */
#include /* srand, rand */
#include /* time */
int main()
{
printf("First number: %d\n", rand() % 100);
srand(time(NULL));
printf("Random number: %d\n", rand() % 100);
srand(1);
printf("Again the first number: %d\n", rand() % 100);
return 0;
}
Possible output:
First number: 83
Random number: 66
Again the first number: 83
2.3 srand
//============================================================================
// Name : srand
// Author : Yongqiang Cheng
// Version : Version 1.0.0
// Copyright : Copyright (c) 2019 Yongqiang Cheng
// Description : Hello World in C++, Ansi-style
//============================================================================
#include /* printf, NULL */
#include /* srand, rand */
#include /* time */
int main()
{
printf("the first number: %d\n", rand() % 100);
printf("the second number: %d\n", rand() % 100);
printf("the third number: %d\n\n", rand() % 100);
srand(time(NULL));
printf("random number 1: %d\n", rand() % 100);
printf("random number 2: %d\n", rand() % 100);
printf("random number 3: %d\n\n", rand() % 100);
srand(1);
printf("again the first number: %d\n", rand() % 100);
printf("again the second number: %d\n", rand() % 100);
printf("again the third number: %d\n", rand() % 100);
return 0;
}
Possible output:
the first number: 83
the second number: 86
the third number: 77
random number 1: 58
random number 2: 10
random number 3: 59
again the first number: 83
again the second number: 86
again the third number: 77
References
https://en.cppreference.com/w/c/numeric/random/srand
http://www.cplusplus.com/reference/cstdlib/srand/