"auto" used to mean automatic memory management because if you are coming from assembly or even some other older higher-level languages you can't just declare a local variable and use it as you please. You must declare somewhere to store it and manage its lifetime (even if that means everything is global).
C and its contemporaries introduced automatic or in modern terms local or stack allocated values, often with lexically-scoped lifetimes. extern meaning something outside this file declares the storage for it and register meaning the compiler should keep the value in a register.
However auto has always been the default and thus redundant and style-wise almost no one ever had the style of explicitly specifying auto so it was little-used in the wild. So the C23 committee adopted auto to mean the same as C++: automatically infer the type of the declaration.
You can see some of B's legacy in the design of C. Making everything int by default harkens back to B's lack of types because everything was a machine word you could interpret however you wanted.
Also with original C's function declarations which don't really make sense. The prototype only declares the name and the local function definition then defines (between the closing paren and the opening brace) the list of parameters and their types. There was no attempt whatsoever to have the compiler verify you passed the correct number or types of parameters.
C and its contemporaries introduced automatic or in modern terms local or stack allocated values, often with lexically-scoped lifetimes. extern meaning something outside this file declares the storage for it and register meaning the compiler should keep the value in a register.
However auto has always been the default and thus redundant and style-wise almost no one ever had the style of explicitly specifying auto so it was little-used in the wild. So the C23 committee adopted auto to mean the same as C++: automatically infer the type of the declaration.
You can see some of B's legacy in the design of C. Making everything int by default harkens back to B's lack of types because everything was a machine word you could interpret however you wanted.
Also with original C's function declarations which don't really make sense. The prototype only declares the name and the local function definition then defines (between the closing paren and the opening brace) the list of parameters and their types. There was no attempt whatsoever to have the compiler verify you passed the correct number or types of parameters.