c++ array shuffle not working

Question

I'm trying to shuffle array of strings and been getting the same array back after trying random_shuffle as below.

std::string arr[5] = {"a","b","c","d","e"};
random_shuffle(std::begin(arr), std::end(arr));

The shuffled array is in the same order in multiple execution of my program when I print it out.

Answer 1

You probably forgot to seed the random generator. This should be called at least and preferably once. Preferably at the beginning of the program.

std::srand(std::time(0));

Answer 2

In std::random_shuffle the random number generator is implementation-defined, but the function std::rand is often used.

Unless you use std::srand to seed the RNG, you will get the same shuffled order everytime you run the program.

One possible fix is to use std::srand with std::time as suggested by kake_fisk in this answer .