How Can I Generate Truly Random Numbers in C Using `rand()`?

Understanding the Behavior of rand() and Implementing Truly Random Number Generation

When running a program that utilizes the rand() function to generate random numbers, users may encounter a consistent sequence of results across different program runs. This behavior arises from the default state of rand(), where it generates pseudorandom numbers based on a fixed seed.

Addressing the Issue of Repetitive Random Sequences

To obtain genuine random numbers, it is crucial to set a seed for the random number generator. By calling srand((unsigned int)time(NULL)) before using rand(), you initialize the seed with the current time, ensuring that the seed is different for each program execution.

Behind-the-Scenes Mechanics of rand()

The rand() function is a pseudorandom number generator, meaning it produces a deterministic sequence that appears random due to mathematical transformations. Each invocation of rand() generates a number based on the current seed and a predetermined algorithm. Without setting a seed, the default seed remains constant, resulting in identical number sequences.

Applying srand() for Randomness

By invoking srand((unsigned int)time(NULL)), you set a seed based on the current system time, which provides a unique value for each program execution. This ensures that the sequence of random numbers generated by rand() will differ between runs.

Conclusion

To effectively generate random numbers, it is essential to set the seed using srand(). By providing a unique seed each time, you can obtain genuinely random number sequences that will vary across program executions.

The above is the detailed content of How Can I Generate Truly Random Numbers in C Using `rand()`?. For more information, please follow other related articles on the PHP Chinese website!