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The following type definition improves readability at the expense of introducing a const-correctness issue.  In this example, the const qualifier applies to the typedef itself instead of applying to the underlying object type.  So func does not take a pointer to a const struct obj, but is instead taking a const pointer to a struct obj.

struct obj {
  int i;
  float f;
};
typedef struct obj *ObjectPtr;
 
void func(const ObjectPtr o); {
  /* Can actually modify o's contents, against expectations. */
}

Compliant Solution

This compliant solution makes use of type definitions, but does not declare a pointer type and so cannot be used in a const-incorrect manner.

struct obj {
  int i;
  float f;
};
typedef struct obj Object;
 
void func(const Object *o);

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 {
  /* Cannot modify o's contents. */
}

Noncompliant Code Example (Windows)

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#include <Windows.h>
 
void func(const LPSTR str) {
  /* Use,Can butmutate do not mutate, strstr's contents, against expectations. */
}

Compliant Solution (Windows)

The compliant solution demonstrates a common naming convention found in the Win32 APIs to utilize , using the proper const type.

#include <Windows.h>
 
void func(LPCSTR str) {
  /* Use,Cannot butmodify do not mutate, str str's contents. */
}

Noncompliant Code Example (Windows) 

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#include <Windows.h>
 
void func(const LPPOINT pt) {
  /* Can modify pt's contents, against expectations. */
}

Compliant Code Example (Windows)

#include <Windows.h>
 
typedef const POINT *LPCPOINT;
void func(LPCPOINT pt) {
  /* Cannot modify pt's contents. */
}

Exceptions

Function pointer types are an exception to this recommendation. 

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