c_str() vs. data() in Standard String Implementations

The distinction between c_str() and data() functions in STL and similar implementations is widely believed to be based on null termination. Supposedly, c_str() always provides a null-terminated string, while data() does not.

However, in practice, implementations often collapse this distinction by making data() call c_str() internally. This may lead to perplexity regarding the actual difference between the two functions.

Correct Usage and Scenarios

The documentation emphatically states that c_str() should be used when a null-terminated string is required. If a non-null-terminated string is acceptable, data() can be used, as it may offer better performance in specific implementations.

Beyond Character-Based Strings

It's crucial to note that strings in C are not limited to character data. They can contain elements of any type. In such cases, data() becomes more meaningful as it directly accesses the underlying data, while c_str() is less relevant due to its emphasis on character-based strings.

C 11 and Beyond: Convergence

In C 11 and later versions of the standard, data() is now required to be null-terminated, aligning its behavior with that of c_str(). This eliminates the previous distinction between the two functions, ensuring that they perform the same operation.