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mblen.3p (4054B)

    

  1. '\" et
  2. .TH MBLEN "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
  3. .\"
  4. .SH PROLOG
  5. This manual page is part of the POSIX Programmer's Manual.
  6. The Linux implementation of this interface may differ (consult
  7. the corresponding Linux manual page for details of Linux behavior),
  8. or the interface may not be implemented on Linux.
  9. .\"
  10. .SH NAME
  11. mblen
  12. \(em get number of bytes in a character
  13. .SH SYNOPSIS
  14. .LP
  15. .nf
  16. #include <stdlib.h>
  17. .P
  18. int mblen(const char *\fIs\fP, size_t \fIn\fP);
  19. .fi
  20. .SH DESCRIPTION
  21. The functionality described on this reference page is aligned with the
  22. ISO\ C standard. Any conflict between the requirements described here and the
  23. ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
  24. .P
  25. If
  26. .IR s
  27. is not a null pointer,
  28. \fImblen\fR()
  29. shall determine the number of bytes constituting the character
  30. pointed to by
  31. .IR s .
  32. Except that the shift state of
  33. \fImbtowc\fR()
  34. is not affected, it shall be equivalent to:
  35. .sp
  36. .RS 4
  37. .nf
  39. mbtowc((wchar_t *)0, \fIs\fP, \fIn\fP);
  40. .fi
  41. .P
  42. .RE
  43. .P
  44. The implementation shall behave as if no function defined in this volume of POSIX.1\(hy2017
  45. calls
  46. \fImblen\fR().
  47. .P
  48. The behavior of this function is affected by the
  49. .IR LC_CTYPE
  50. category of the current locale. For a state-dependent encoding, this
  51. function shall be placed into its initial state by a call for which its
  52. character pointer argument,
  53. .IR s ,
  54. is a null pointer. Subsequent calls with
  55. .IR s
  56. as other than a null pointer shall cause the internal state of the
  57. function to be altered as necessary. A call with
  58. .IR s
  59. as a null pointer shall cause this function to return a non-zero value
  60. if encodings have state dependency, and 0 otherwise. If the
  61. implementation employs special bytes to change the shift state, these
  62. bytes shall not produce separate wide-character codes, but shall be
  63. grouped with an adjacent character. Changing the
  64. .IR LC_CTYPE
  65. category causes the shift state of this function to be unspecified.
  66. .P
  67. The
  68. \fImblen\fR()
  69. function need not be thread-safe.
  70. .SH "RETURN VALUE"
  71. If
  72. .IR s
  73. is a null pointer,
  74. \fImblen\fR()
  75. shall return a non-zero or 0 value, if character encodings,
  76. respectively, do or do not have state-dependent encodings. If
  77. .IR s
  78. is not a null pointer,
  79. \fImblen\fR()
  80. shall either return 0 (if
  81. .IR s
  82. points to the null byte), or return the number of bytes that
  83. constitute the character (if the next
  84. .IR n
  85. or fewer bytes form a valid character), or return \-1 (if they do
  86. not form a valid character)
  87. and may set
  88. .IR errno
  89. to indicate the error.
  90. In no case shall the value returned be greater than
  91. .IR n
  92. or the value of the
  93. {MB_CUR_MAX}
  94. macro.
  95. .SH ERRORS
  96. The
  97. \fImblen\fR()
  98. function may fail if:
  99. .TP
  100. .BR EILSEQ
  101. An invalid character sequence is detected. In the POSIX locale an
  102. .BR [EILSEQ] 
  103. error cannot occur since all byte values are valid characters.
  104. .LP
  105. .IR "The following sections are informative."
  106. .SH EXAMPLES
  107. None.
  108. .SH "APPLICATION USAGE"
  109. None.
  110. .SH RATIONALE
  111. None.
  112. .SH "FUTURE DIRECTIONS"
  113. None.
  114. .SH "SEE ALSO"
  115. .IR "\fImbtowc\fR\^(\|)",
  116. .IR "\fImbstowcs\fR\^(\|)",
  117. .IR "\fIwctomb\fR\^(\|)",
  118. .IR "\fIwcstombs\fR\^(\|)"
  119. .P
  120. The Base Definitions volume of POSIX.1\(hy2017,
  121. .IR "\fB<stdlib.h>\fP"
  122. .\"
  123. .SH COPYRIGHT
  124. Portions of this text are reprinted and reproduced in electronic form
  125. from IEEE Std 1003.1-2017, Standard for Information Technology
  126. -- Portable Operating System Interface (POSIX), The Open Group Base
  127. Specifications Issue 7, 2018 Edition,
  128. Copyright (C) 2018 by the Institute of
  129. Electrical and Electronics Engineers, Inc and The Open Group.
  130. In the event of any discrepancy between this version and the original IEEE and
  131. The Open Group Standard, the original IEEE and The Open Group Standard
  132. is the referee document. The original Standard can be obtained online at
  133. http://www.opengroup.org/unix/online.html .
  134. .PP
  135. Any typographical or formatting errors that appear
  136. in this page are most likely
  137. to have been introduced during the conversion of the source files to
  138. man page format. To report such errors, see
  139. https://www.kernel.org/doc/man-pages/reporting_bugs.html .