Why do we need header files?
The primary purpose of a header file is to propagate declarations to code files. Header files allow us to put declarations in one location and then import them wherever we need them. This can save a lot of typing in multi-file programs. This program prints “Hello, world!” to the console using std::cout.
Should every class have a header file?
Each class shall have it’s own header and implementation file. So if we wrote a class called MyString we would need an associated MyStringh.
Do you write using namespace in a header file?
Corollary: In header files, don’t write namespace-level using directives or using declarations; instead, explicitly namespace-qualify all names. A header file is a guest in one or more source files. A header file that includes using directives and declarations brings its rowdy buddies over too. A using declaration brings in one buddy.
Why do you put include in headers first?
Placing #include for the unit header first in the unit body allows the compiler to verify that the header contains all required #include statements. An alternate design, not permitted by this standard, allows no #include statements in headers; all #include s are done in the body files.
When to include headers in a source file?
Probably static code checkers flag this too. The header should include just the headers that it needs to compile. An easy way to enforce this is to always include each source file’s own header as the first thing, before any other headers. Then the source file will fail to compile if the header isn’t self-contained.
Do you include your own header in ANSI C?
In the original ANSI C standard it also stated that a conforming header file must stand alone(include everything it needs). In my C files I include its own header first, this helps to detect these non stand-alone headers (but only helps). It is better to catch them now than later as the effort is less.