strlen, strnlen_s
From cppreference.com
Defined in header
<string.h>
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||
size_t strlen( const char *str );
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(1) | |
(2) | (since C11) | |
1) Returns the length of the given byte string, that is, the number of characters in a character array whose first element is pointed to by
str
up to and not including the first null character. The behavior is undefined if there is no null character in the character array pointed to by str
.
2) Same as (1), except that the function returns zero if
str
is a null pointer and returns strsz
if the null character was not found in the first strsz
bytes of str
.
- As with all bounds-checked functions,
strnlen_s
is only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before includingstring.h
.
Contents |
[edit] Parameters
str | - | pointer to the null-terminated byte string to be examined |
strsz | - | maximum number of characters to examine |
[edit] Return value
1) The length of the null-terminated string
str
.
2) The length of the null-terminated string
str
on success, zero if str
is a null
pointer, strsz
if the null character was not found.[edit] Notes
strnlen_s
and wcsnlen_s
are the only bounds-checked functions that do not invoke the runtime constraints handler. They are pure utility functions used to provide limited support for non-null terminated strings.
[edit] Example
Run this code
Output:
without null character: 45 with null character: 46
[edit] References
- C11 standard (ISO/IEC 9899:2011):
-
- 7.24.6.3 The strlen function (p: 372)
-
- K.3.7.4.4 The strnlen_s function (p: 623)
- C99 standard (ISO/IEC 9899:1999):
-
- 7.21.6.3 The strlen function (p: 334)
- C89/C90 standard (ISO/IEC 9899:1990):
-
- 4.11.6.3 The strlen function
[edit] See also
(C95)(C11)
|
returns the length of a wide string (function) |
returns the number of bytes in the next multibyte character (function) |
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C++ documentation for strlen
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