Is there an easy way to initialize the entire C/C++ array to -1?

int array[100] = {-1};

This code doesn't initialize the entire array to -1 It means, "Please make only the first element in the array -1 and initialize all other unspecified elements to zero."

I'll write down the code that initializes the entire array to the same value because C and C++ are slightly different.

First of all, you can see [How to initialize the C array] for C language.

If you use GCC other than that,

int array[100] = { [0 ... 99] = -1 };

It's possible.

A typical code that can only be written in C++ is std::fill_n in the header.

std::fill_n(array, 100, -1);