Why should one use std::string over c-style strings in C++?

Question

"One should always use std::string over c-style strings(char *)" is advice that comes up for almost every source code posted here. While the advice is no doubt good, the actual questions being addressed do not permit to elaborate on the why? aspect of the advice in detail. This question is to serve as a placeholder for the same.

A good answer should cover the following aspects(in detail):

1. Why should one use std::string over c-style strings in C++?
2. What are the disadvantages (if any) of the practice mentioned in #1?
3. What are the scenarios where the opposite of the advice mentioned in #1 is a good practice?

Answer 1

1. std::string manages its own memory, so you can copy, create, destroy them easily.
2. You can't use your own buffer as a std::string.
3. You need to pass a c string / buffer to something that expects to take ownership of the buffer - such as a 3rd party C library.

Answer 2

Well, if you just need an array of chars, std::string provides little advantage. But face it, how often is that the case? By wrapping a char array with additional functionality like std::string does, you gain both power and efficiency for some operations.

For example, determining the length of an array of characters requires "counting" the characters in the array. In contrast, an std::string provides an efficient operation for this particular task. (see https://stackoverflow.com/a/1467497/129622)

1. For power, efficiency and sanity
2. Larger memory footprint than "just" a char array
3. When you just need an array of chars