This documentation is archived and is not being maintained.


Use this function to determine whether a pointer to a string is valid.

BOOL AfxIsValidString(
   LPCSTR lpsz,
   int nLength = -1 


The pointer to test.
Specifies the length of the string to be tested, in bytes. A value of –1 indicates that the string will be null-terminated.

Return Value

In debug builds, nonzero if the specified pointer points to a string of the specified size; otherwise 0.

In non-debug builds, nonzero if lpsz is not NULL; otherwise 0.


// Create a character string which should be valid.
char str[12] = "hello world";

// Create a null pointer, which should be an invalid string.
char *null = (char *)0x0;

ASSERT(AfxIsValidString(str, 12));
ASSERT(!AfxIsValidString(null, 5));

See Also

MFC Macros and Globals | AfxIsMemoryBlock | AfxIsValidAddress