Perl srand()用法及代码示例

Perl中的srand()函数可帮助rand()函数在每次运行程序时生成一个恒定值。
每次调用rand()函数以获取恒定的随机值时，此srand()函数使用相同的参数。

用法： srand(seed)

参数：
seed :它是一个整数值。

返回：该函数不返回任何值。

示例1:

#!/usr/bin/perl 
  
# Calling the srand() function and  
# Printing a random value  
srand(5); 
print("The first random number is ", rand(), ".\n"); 
  
# Calling the srand() function and  
# Printing a random value  
srand(5); 
print("The second random number is ", rand(), ".\n"); 
  
# Calling the srand() function and  
# Printing a random value  
srand(5); 
print("The third random number is ", rand(), ".\n"); 
  
# Calling the srand() function and  
# Printing a random value  
srand(5); 
print("The fourth random number is ", rand(), ".\n");

输出：

The first random number is 0.524839579434232.
The second random number is 0.524839579434232.
The third random number is 0.524839579434232.
The fourth random number is 0.524839579434232.

注意：在上面的代码中，可以看出srand()函数的参数是相同的，这就是为什么rand()函数每次调用时都产生相同的随机值的原因。

示例2:

#!/usr/bin/perl 
  
# Calling the srand() function and  
# Printing a random value  
srand(5); 
print("The first random number is ", rand(), ".\n"); 
  
# Calling the srand() function and  
# Printing a random value  
srand(6); 
print("The second random number is ", rand(), ".\n"); 
  
# Calling the srand() function and  
# Printing a random value  
srand(7); 
print("The third random number is ", rand(), ".\n"); 
  
# Calling the srand() function and  
# Printing a random value  
srand(8); 
print("The fourth random number is ", rand(), ".\n");

输出：

The first random number is 0.524839579434232.
The second random number is 0.395641888099821.
The third random number is 0.266444196765409.
The fourth random number is 0.137246505430998.

注意：在上面的代码中，可以看出srand()函数具有不同的参数，这就是为什么rand()函数每次调用时都会产生不同的随机值的原因。

示例3:

#!/usr/bin/perl 
  
# Printing a random value without calling the srand() function 
print("The first random number is ", rand(), ".\n"); 
  
# Printing a random value without calling the srand() function 
print("The second random number is ", rand(), ".\n"); 
  
# Printing a random value without calling the srand() function 
print("The third random number is ", rand(), ".\n"); 
  
# Printing a random value without calling the srand() function 
print("The fourth random number is ", rand(), ".\n");

输出：

The first random number is 0.241482914266275.
The second random number is 0.821264154368208.
The third random number is 0.870625858233449.
The fourth random number is 0.012084407123389.

注意：在上面的代码中，可以看出未使用srand()函数，这就是为什么rand()函数每次调用时都会产生不同的随机值的原因。

相关用法

注：本文由纯净天空筛选整理自Kanchan_Ray大神的英文原创作品 Perl | srand() Function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。