How do you initialise a dynamic array in C++?

Solution 1:

char* c = new char[length]();

Solution 2:

Two ways:

char *c = new char[length];
std::fill(c, c + length, INITIAL_VALUE);
// just this once, since it's char, you could use memset

Or:

std::vector<char> c(length, INITIAL_VALUE);

In my second way, the default second parameter is 0 already, so in your case it's unnecessary:

std::vector<char> c(length);

[Edit: go vote for Fred's answer, char* c = new char[length]();]

Solution 3:

Maybe use std::fill_n()?

char* c = new char[length];
std::fill_n(c,length,0);

Solution 4:

The array form of new-expression accepts only one form of initializer: an empty (). This, BTW, has the same effect as the empty {} in your non-dynamic initialization.

The above applies to pre-C++11 language. Starting from C++11 one can use uniform initialization syntax with array new-expressions

char* c = new char[length]{};
char* d = new char[length]{ 'a', 'b', 'c' };