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Perl | srand() Function

  • Last Updated : 07 May, 2019

The srand() function in Perl helps rand() function to generate a constant value each time the program is run.
This srand() function uses the same parameter each time the rand() function is called for getting constant random value.

Syntax: srand(seed)

Parameters:
seed : It is an integer value.

Return: This function does not return any value.

Example 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");


Output:

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.

Note: In the above code, it can be seen that the parameter of srand() function is same that is why the rand() function produced the same random value each time it is called.

Example 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");

Output :

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.

Note: In the above code, it can be seen that the srand() functions are having a different parameter that is why the rand() function produced the different random value each time it is called.

Example 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");

Output :

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.

Note: In the above code, it can be seen that the srand() functions are not used that is why the rand() function produced the different random value each time it is called.




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