Generating Random Numbers in C++

In summary, to generate a random number in C++, you can use the rand() function from the cstdlib library, and to generate a random number within a specific range, you can use the formula rand() % (max - min + 1) + min or the uniform_int_distribution class. To generate a random floating-point number, you can type cast the result of rand() or use the uniform_real_distribution class. To generate a random string, you can use the rand() function with a loop or the uniform_int_distribution class. The rand() function is not truly random, but can be sufficiently random for most applications. For a higher level of randomness, you can use the random_device class from the random library.
  • #1
chmate
37
0
Hello!

I've been trying to create an algorithm which picks a number randomly from array. P.S i have an array like A={1,4,-1,3,-7,2,-14} and I want to pick a number randomly from array.

Any idea?

Thank you.
 
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  • #2
Why don't you use rand() to draw index?
 
  • #3
Hi borek, can you show me an example?

Thank you.
 
  • #4
Hello!

I've solved my problem. I've been looking for this part of code:

srand(time(NULL));
random = arr[rand() % (sizeof(arr) / sizeof(arr[0]))];

Thank you.
 
  • #5


Hello there!

Generating random numbers in C++ can be achieved using the standard library function "rand()" which generates a pseudo-random number. To pick a random number from an array, you can use the "rand()" function to generate a random index within the size of your array and then access the element at that index. For example, you can use the "rand() % size" to generate a random index within the range of your array size and then access the element at that index using A[index]. This will give you a random number from your array. However, keep in mind that this method may not always produce truly random numbers and may require further tweaking for more precise results. I hope this helps!
 

1. How do I generate a random number in C++?

To generate a random number in C++, you can use the rand() function from the cstdlib library. This function will generate a random integer between 0 and RAND_MAX, which is a constant defined in the library. To get a different random number each time, you can use the srand() function to seed the random number generator with a different value.

2. How do I generate a random number within a specific range in C++?

To generate a random number within a specific range, you can use the formula rand() % (max - min + 1) + min, where max is the maximum value and min is the minimum value. This will generate a random number between min and max, inclusive. You can also use the uniform_int_distribution class from the random library to generate a random number within a specific range.

3. How can I generate a random floating-point number in C++?

To generate a random floating-point number in C++, you can use the rand() function along with type casting to convert the random integer into a floating-point number. For example, static_cast<float>(rand()) / RAND_MAX will generate a random float between 0 and 1. You can also use the uniform_real_distribution class from the random library to generate a random floating-point number within a specific range.

4. How do I generate a random string in C++?

To generate a random string in C++, you can use the rand() function along with a loop to generate a random number for each character in the string. You can also use the uniform_int_distribution class to generate a random ASCII character and add it to the string. Alternatively, you can use the random_device class from the random library to generate a string of random numbers and then convert them to characters.

5. Is the rand() function truly random?

The rand() function is not truly random, as it is based on a deterministic algorithm. However, it can produce a sufficiently random sequence of numbers for most applications. If you need a higher level of randomness, you can use the random_device class from the random library, which generates random numbers based on a hardware source, making them more unpredictable.

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