Question

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Difference between string.h and cstring?

What is better programming practice in C++ when including the standard header files with respect to

including cmath in place of math.h or vice-versa?

including cstring in place of string.h or vice-versa?

and for other <c*> and <*.h> header files which apparently seem to accomplish the same thing?

Answer 1

<cstring> is newer; <string.h> is really there for backwards compatibility (and for C, of course). The difference is that <cstring> puts the string functions in the std namespace, while <string.h> puts them in the global namespace.

In addition, <cstring> changes the types of certain functions to promote type-safety. E.g., the C declaration

char *strchr(char const *, int);

is replaced by the overloads (in the std namespace)

char       *strchr(char       *, int);
char const *strchr(char const *, int);

In the case of <cmath> there are further differences with <math.h> which make <cmath> more idiomatic and less C-like.

Prefer <cstring> for new code and use the std:: prefix on the functions.