Question

I need help in understanding when shall I use the following options

char *a = new char();

and

char *a = new char[sizeof(int)+1];

and how the respective memory freeing calls should be made?

Answer 1

The fist one allocates a single char. You delete it with:

delete a;

The second one allocates an array of chars. The length you have chosen is a little strange. You deallocate it with:

delete[] a;

Now… I hope you don’t think you can put a stringified number in the second a (something like "123456", because you’ll need many more bytes. Let’s say at least 12 if an int is 32 bits. There is a funny formula to calculate the minimum length necessary. It’s an approximation of the log10 https://stackoverflow.com/a/2338397/613130

To be clear, on my machine sizeof(int) == 4, but in an int I can put -2147483648 that is 10 digits plus the -, so 11 (plus the zero terminator)