Two types of data structures are supported for string manipulation:
Multibyte strings
Wide-character strings
Multibyte strings are encoded in native Oracle character sets. Functions that operate on multibyte strings take the string as a whole unit with the length of the string calculated in bytes. Wide-character (wchar
) string functions provide more flexibility in string manipulation. They support character-based and string-based operations with the length of the string calculated in characters.
The wide-character data type is Oracle-specific and should not be confused with the wchar_t
data type defined by the ANSI/ISO C standard. The Oracle wide-character data type is always 4 bytes in all operating systems, whereas the size of wchar_t
depends on the implementation and the operating system. The Oracle wide-character data type normalizes multibyte characters so that they have a fixed width for easy processing. This guarantees no data loss for round-trip conversion between the Oracle wide-character set and the native character set.
String manipulation can be classified into the following categories:
Conversion of strings between multibyte and wide character
Character classifications
Case conversion
Calculations of display length
General string manipulation, such as comparison, concatenation, and searching
Table 22-4 summarizes the OCI string manipulation functions, which are described in this section.
Table 22-4 OCI String Manipulation Functions
Function | Purpose |
---|---|
Convert part of a multibyte string into the wide-character string |
|
Convert a multibyte string into the specified case and copies the result into the destination array |
|
Append a multibyte string to the destination string |
|
Compare two multibyte strings by binary, linguistic, or case-insensitive comparison methods |
|
Copy a multibyte string into the destination array. It returns the number of bytes copied. |
|
Return the number of bytes in a multibyte string |
|
Append, at most, n bytes from a multibyte string to the destination string |
|
Compare two multibyte strings by binary, linguistic, or case-insensitive comparison methods. Each string is in the specified length |
|
Copy a specified number of bytes of a multibyte string into the destination array |
|
Return the number of display positions occupied by the multibyte string within the range of n bytes |
|
Convert a |
|
Convert part of a wide-character string to the multibyte string |
|
Determine the number of bytes required for a wide character in multibyte encoding |
|
Convert a wide-character string into the specified case and copies the result into the destination array |
|
Append a wide-character string to the destination string |
|
Search for the first occurrence of a wide character in a string. Return a point to the wide character if the search is successful. |
|
Compare two wide-character strings by binary, linguistic, or case-insensitive comparison methods |
|
Copy a wide-character string into a destination array. Return the number of characters copied. |
|
Return the number of characters in a wide-character string |
|
Append, at most, n characters from a wide-character string to the destination string |
|
Compare two wide-character strings by binary, linguistic, or case-insensitive methods. Each string is a specified length. |
|
Copy, at most, n characters of a wide-character string into the destination array |
|
Search for the last occurrence of a character in a wide-character string |
|
Convert a specified wide character into the corresponding lowercase character |
|
Convert a |
|
Convert a specified wide character into the corresponding uppercase character |
sword OCIMultiByteInSizeToWideChar ( void *hndl, OCIWchar *dst, size_t dstsz, const OraText *src, size_t srcsz, size_t *rsize );
OCI environment or user session handle to determine the character set of the string.
Pointer to a destination buffer for wchar
. It can be a NULL
pointer when dstsz
is zero.
Destination buffer size in number of characters. If it is zero, then this function returns the number of characters needed for the conversion.
Source string to be converted.
Length of source string in bytes.
Number of characters written into the destination buffer, or number of characters for the converted string if dstsz
is zero. If it is a NULL
pointer, then nothing is returned.
This routine converts part of a multibyte string into the wide-character string. It converts as many complete characters as it can until it reaches the output buffer size limit or input buffer size limit or it reaches a NULL
terminator in a source string. The output buffer is NULL
-terminated if space permits. If dstsz
is zero, then this function returns only the number of characters not including the ending NULL
terminator needed for a converted string. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Converts the multibyte string pointed to by srcstr
into uppercase or lowercase as specified by the flag and copies the result into the array pointed to by dststr
.
size_t OCIMultiByteStrCaseConversion ( void *hndl, OraText *dststr, const OraText *srcstr, ub4 flag );
OCI environment or user session handle.
Pointer to destination array. The result string is NULL
-terminated.
Pointer to source string.
Specify the case to which to convert:
OCI_NLS_UPPERCASE
: Convert to uppercase.
OCI_NLS_LOWERCASE
: Convert to lowercase.
This flag can be used with OCI_NLS_LINGUISTIC
to specify that the linguistic setting in the locale is used for case conversion.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate()
function, then this function produces an error.
Appends a copy of the multibyte string pointed to by srcstr
to the end of the string pointed to by dststr
.
OCI environment or user session handle to determine the character set.
Pointer to the destination multibyte string for appending. The output buffer is NULL
-terminated.
Pointer to the source string to append.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Compares two multibyte strings by binary, linguistic, or case-insensitive comparison methods.
OCI environment or user session handle.
Pointer to a NULL
-terminated string.
Pointer to a NULL
-terminated string.
It is used to decide the comparison method. It can take one of these values:
OCI_NLS_BINARY
: Binary comparison This is the default value.
OCI_NLS_LINGUISTIC
: Linguistic comparison specified in the locale.
This flag can be used with OCI_NLS_CASE_INSENSITIVE
for case-insensitive comparison. For example, use OCI_NLS_LINGUISTIC|OCI_NLS_CASE_INSENSITIVE
to compare strings linguistically without regard to case.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
The return values for the function are:
0, if str1 = str2
Positive, if str1 > str2
Negative, if str1 < str2
Pointer to the OCI environment or user session handle.
Pointer to the destination buffer. The output buffer is NULL
-terminated.
Pointer to the source multibyte string.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Returns the number of bytes in the multibyte string pointed to by str
, not including the NULL
terminator.
Pointer to the OCI environment or user session handle.
Pointer to the source multibyte string.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Pointer to OCI environment or user session handle.
Pointer to the destination multibyte string for appending.
Pointer to the source multibyte string to append.
The number of bytes from srcstr
to append.
This function is similar to OCIMultiByteStrcat(). At most, n bytes from srcstr
are appended to dststr
. Note that the NULL
terminator in srcstr
stops appending, and the function appends as many character as possible within n
bytes. The dststr
parameter is NULL
-terminated. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Compares two multibyte strings by binary, linguistic, or case-insensitive comparison methods. A length is specified for each string.
int OCIMultiByteStrncmp ( void *hndl, const OraText *str1, size_t len1, OraText *str2, size_t len2, int flag );
OCI environment or user session handle.
Pointer to the first string.
The length of the first string to compare.
Pointer to the second string.
The length of the second string to compare.
It is used to decide the comparison method. It can take one of these values:
OCI_NLS_BINARY
: Binary comparison. This is the default value.
OCI_NLS_LINGUISTIC
: Linguistic comparison specified in the locale.
This flag can be used with OCI_NLS_CASE_INSENSITIVE
for case-insensitive comparison. For example, use OCI_NLS_LINGUISTIC|OCI_NLS_CASE_INSENSITIVE
to compare strings linguistically without regard to case.
This function is similar to OCIMultiByteStrcmp(), except that, at most, len1
bytes from str1
and len2
bytes from str2
are compared. The NULL
terminator is used in the comparison. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
The return values for the function are:
0, if str1
= str2
Positive, if str1
> str2
Negative, if str1
< str2
Pointer to OCI environment or user session handle.
Pointer to the source multibyte string.
Pointer to the destination buffer.
The number of bytes from srcstr
to copy.
This function is similar to OCIMultiByteStrcpy(). At most, n bytes are copied from the array pointed to by srcstr
to the array pointed to by dststr
. Note that the NULL
terminator in srcstr
stops copying, and the function copies as many characters as possible within n
bytes. The result string is NULL
-terminated. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Returns the number of display positions occupied by the multibyte string within the range of n
bytes.
OCI environment or user session handle.
Pointer to a multibyte string.
The number of bytes to examine.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
sword OCIMultiByteToWideChar ( void *hndl, OCIWchar *dst, const OraText *src, size_t *rsize );
OCI environment or user session handle to determine the character set of the string.
Destination buffer for wchar
.
Source string to be converted.
Number of characters converted, including NULL
terminator. If it is a NULL
pointer, then nothing is returned.
The wchar
output buffer is NULL
-terminated. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
sword OCIWideCharInSizeToMultiByte ( void *hndl, OraText *dst, size_t dstsz, const OCIWchar *src, size_t srcsz, size_t *rsize );
OCI environment or user session handle to determine the character set of string.
Destination buffer for multibyte. It can be a NULL
pointer if dstsz
is zero.
Destination buffer size in bytes. If it is zero, then the function returns the size in bytes need for converted string.
Source wchar
string to be converted.
Length of source string in characters.
Number of bytes written into destination buffer, or number of bytes needed to store the converted string if dstsz
is zero. If it is a NULL
pointer, then nothing is returned.
Converts part of a wide-character string into the multibyte format. It converts as many complete characters as it can until it reaches the output buffer size or the input buffer size or until it reaches a NULL
terminator in the source string. The output buffer is NULL
-terminated if space permits. If dstsz
is zero, then the function returns the size in bytes, not including the NULL
terminator needed to store the converted string. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
OCI environment or user session handle to determine the character set.
The wchar
character.
If OCI_UTF16ID
is specified for SQL CHAR
data in OCIEnvNlsCreate() function, then this function produces an error.
Converts a wide-character string into a specified case and copies the result into the destination array.
size_t OCIWideCharStrCaseConversion ( void *hndl, OraText *dststr, const OraText *srcstr, ub4 flag );
OCI environment or user session handle.
Pointer to destination array. The result string is NULL
-terminated.
Pointer to source string.
Specify the case to which to convert:
OCI_NLS_UPPERCASE
: Convert to uppercase.
OCI_NLS_LOWERCASE
: Convert to lowercase.
This flag can be used with OCI_NLS_LINGUISTIC
to specify that the linguistic setting in the locale is used for case conversion.
Converts the wide-character string pointed to by srcstr
into uppercase or lowercase as specified by the flag and copies the result into the array pointed to by dststr
. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Appends the wide-character string pointed to by wsrcstr
to the wide-character string pointed to by wdststr
.
OCI environment or user session handle to determine the character set.
Pointer to the destination wchar
string. The output buffer is NULL
-terminated.
Pointer to the source wide-character string to append.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
OCI environment or user session handle to determine the character set.
Pointer to the wchar
string to search.
The wchar
to search for.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Compares two wide-character strings by binary (based on wchar
encoding value), linguistic, or case-insensitive comparison methods.
int OCIWideCharStrcmp ( void *hndl, const OCIWchar *wstr1, const OCIWchar *wstr2, int flag );
OCI environment or user session handle to determine the character set.
Pointer to a NULL
-terminated wchar
string.
Pointer to a NULL
-terminated wchar
string.
Used to decide the comparison method. It can take one of these values:
OCI_NLS_BINARY
: Binary comparison. This is the default value.
OCI_NLS_LINGUISTIC
: Linguistic comparison specified in the locale definition.
This flag can be used with OCI_NLS_CASE_INSENSITIVE
for case-insensitive comparison. For example, use OCI_NLS_LINGUISTIC|OCI_NLS_CASE_INSENSITIVE
to compare strings linguistically without regard to case.
The UNICODE_BINARY sort method cannot be used with OCIWideCharStrcmp()
to perform a linguistic comparison of supplied wide-character arguments.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
The return values for the function are:
0, if wstr1 = wstr2
Positive, if wstr1 > wstr2
Negative, if wstr1 < wstr2
OCI environment or user session handle to determine the character set.
Pointer to the destination wchar
buffer. The result string is NULL
-terminated.
Pointer to the source wchar
string.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
OCI environment or user session handle to determine the character set.
Pointer to the source wchar
string.
Returns the number of characters in the wchar
string pointed to by wstr
, not including the NULL
terminator. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
size_t OCIWideCharStrncat ( void *hndl, OCIWchar *wdststr, const OCIWchar *wsrcstr, size_t n );
OCI environment or user session handle to determine the character set.
Pointer to the destination wchar
string.
Pointer to the source wchar
string.
Number of characters from wsrcstr
to append.
This function is similar to OCIWideCharStrcat(). At most, n characters from wsrcstr
are appended to wdststr
. Note that the NULL
terminator in wsrcstr
stops appending. The wdststr
parameter is NULL
-terminated. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Compares two wide-character strings by binary, linguistic, or case-sensitive methods. Each string has a specified length.
int OCIWideCharStrncmp ( void *hndl, const OCIWchar *wstr1, size_t len1, const OCIWchar *wstr2, size_t len2, int flag );
OCI environment or user session handle to determine the character set.
Pointer to the first wchar
string.
The length from the first string for comparison.
Pointer to the second wchar
string.
The length from the second string for comparison.
It is used to decide the comparison method. It can take one of these values:
OCI_NLS_BINARY
: For the binary comparison, this is default value.
OCI_NLS_LINGUISTIC
: For the linguistic comparison specified in the locale.
This flag can be used with OCI_NLS_CASE_INSENSITIVE
for case-insensitive comparison. For example, use OCI_NLS_LINGUISTIC
|OCI_NLS_CASE_INSENSITIVE
to compare strings linguistically without regard to case.
This function is similar to OCIWideCharStrcmp(). It compares two wide-character strings by binary, linguistic, or case-insensitive comparison methods. At most, len1
bytes from wstr1
and len2
bytes from wstr2
are compared. The NULL
terminator is used in the comparison. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
The UNICODE_BINARY sort method cannot be used with OCIWideCharStrncmp()
to perform a linguistic comparison of supplied wide-character arguments.
The return values for the function are:
0, if wstr1 = wstr2
Positive, if wstr1 > wstr2
Negative, if wstr1 < wstr2
size_t OCIWideCharStrncpy ( void *hndl, OCIWchar *wdststr, const OCIWchar *wsrcstr, size_t n );
OCI environment or user session handle to determine the character set.
Pointer to the destination wchar
buffer.
Pointer to the source wchar
string.
Number of characters from wsrcstr
to copy.
This function is similar to OCIWideCharStrcpy(), except that, at most, n characters are copied from the array pointed to by wsrcstr
to the array pointed to by wdststr
. Note that the NULL
terminator in wdststr
stops copying, and the result string is NULL
-terminated. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
OCI environment or user session handle to determine the character set.
Pointer to the wchar
string to search in.
The wchar
to search for.
Searches for the last occurrence of wc
in the wchar
string pointed to by wstr
. If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Converts the wide-character string specified by wc
into the corresponding lowercase character, if it exists, in the specified locale. If no corresponding lowercase character exists, then it returns wc
itself.
OCI environment or user session handle to determine the character set.
The wchar
for lowercase conversion.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
sword OCIWideCharToMultiByte ( void *hndl, OraText *dst, const OCIWchar *src, size_t *rsize );
OCI environment or user session handle to determine the character set of the string.
Destination buffer for a multibyte string. The output buffer is NULL
-terminated.
Source wchar
string to be converted.
Number of bytes written into destination buffer. If it is a NULL
pointer, then nothing is returned.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.
Converts the wide-character string specified by wc
into the corresponding uppercase character, if it exists, in the specified locale. If no corresponding uppercase character exists, then it returns wc
itself.
OCI environment or user session handle to determine the character set.
The wchar
for uppercase conversion.
If OCI_UTF16ID
is specified for SQL CHAR
data in the OCIEnvNlsCreate() function, then this function produces an error.