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# mblen

From cppreference.com
< c‎ | string‎ | multibyte

Defined in header `<stdlib.h>` |  |
int mblen( const char* s, size_t n ); |  |

Determines the size, in bytes, of the multibyte character whose first byte is pointed to by `s`.

If `s` is a null pointer, resets the global conversion state and determined whether shift sequences are used.

This function is equivalent to the call mbtowc((wchar_t*)0, s, n), except that conversion state of mbtowc is unaffected.

### [edit] Notes

Each call to `mblen` updates the internal global conversion state (a static object of type mbstate_t, only known to this function). If the multibyte encoding uses shift states, care must be taken to avoid backtracking or multiple scans. In any case, multiple threads should not call `mblen` without synchronization: mbrlen may be used instead.

### [edit] Parameters

s | - | pointer to the multibyte character
n | - | limit on the number of bytes in s that can be examined

### [edit] Return value

If `s` is not a null pointer, returns the number of bytes that are contained in the multibyte character or -1 if the first bytes pointed to by `s` do not form a valid multibyte character or ​0​ if `s` is pointing at the null charcter '\0'.

If `s` is a null pointer, resets its internal conversion state to represent the initial shift state and returns ​0​ if the current multibyte encoding is not state-dependent (does not use shift sequences) or a non-zero value if the current multibyte encoding is state-dependent (uses shift sequences).

### [edit] Example

| This section is incomplete Reason: no example

### [edit] See also

mbtowc | converts the next multibyte character to wide character (function) [edit]
mbrlen | returns the number of bytes in the next multibyte character, given state (function) [edit]
C++ documentation for mblen

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