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struct string_mx {
size_t size;
size_t maxsize;
unsigned char strtype;
char *cstr;
};
typedef struct string_mx string_mx;
/* Function declarations */
extern errno_t strcpy_m(string_mx *s1, const string_mx *s2);
extern errno_t strcat_m(string_mx *s1, const string_mx *s2) ;
/* etc. */
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The implementation of the string_mx type is fully visible to the user of the data type after including the string_m.h file. Programmers are consequently more likely to directly manipulate the fields within the structure, violating the software engineering principles of information hiding and data encapsulation and increasing the probability of developing incorrect or nonportable code.
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This compliant solution reimplements the string_mx type as a private type, hiding the implementation of the data type from the user of the managed string library. To accomplish this, the developer of the private data type creates two header files: an external "string_m.h" header file that is included by the user of the data type and an internal file that is included only in files that implement the managed string abstract data type.
In the external string_m.h file, the struct string_mx type is typedef defined to be an instance of struct string_mx datatype, which in turn is declared as an incomplete type.
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