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Contents

  • Foreword
  • Introduction
  • 1. Scope
  • 2. Normative references
  • 3. Terms, definitions, and symbols
  • 4. Conformance
  • 5. Environment
  • 6. Language
  • 7. Library
    • 7.1 Introduction
    • 7.2 Diagnostics <assert.h>
    • 7.3 Complex arithmetic <complex.h>
    • 7.4 Character handling <ctype.h>
      • 7.4.1 Character classification functions
        • 7.4.1.1 The isalnum function
        • 7.4.1.2 The isalpha function
        • 7.4.1.3 The isblank function
        • 7.4.1.4 The iscntrl function
        • 7.4.1.5 The isdigit function
        • 7.4.1.6 The isgraph function
        • 7.4.1.7 The islower function
        • 7.4.1.8 The isprint function
        • 7.4.1.9 The ispunct function
        • 7.4.1.10 The isspace function
        • 7.4.1.11 The isupper function
        • 7.4.1.12 The isxdigit function
      • 7.4.2 Character case mapping functions
    • 7.5 Errors <errno.h>
    • 7.6 Floating-point environment <fenv.h>
    • 7.7 Characteristics of floating types <float.h>
    • 7.8 Format conversion of integer types <inttypes.h>
    • 7.9 Alternative spellings <iso646.h>
    • 7.10 Sizes of integer types <limits.h>
    • 7.11 Localization <locale.h>
    • 7.12 Mathematics <math.h>
    • 7.13 Nonlocal jumps <setjmp.h>
    • 7.14 Signal handling <signal.h>
    • 7.15 Variable arguments <stdarg.h>
    • 7.16 Boolean type and values <stdbool.h>
    • 7.17 Common definitions <stddef.h>
    • 7.18 Integer types <stdint.h>
    • 7.19 Input/output <stdio.h>
    • 7.20 General utilities <stdlib.h>
    • 7.21 String handling <string.h>
    • 7.22 Type-generic math <tgmath.h>
    • 7.23 Date and time <time.h>
    • 7.24 Extended multibyte and wide character utilities <wchar.h>
    • 7.25 Wide character classification and mapping utilities <wctype.h>
    • 7.26 Future library directions
  • Annex A
  • Annex B
  • Annex C
  • Annex D
  • Annex E
  • Annex F
  • Annex G
  • Annex H
  • Annex I
  • Annex J
  • Bibliography
C99 Language Standard
  • 7. Library
  • 7.4 Character handling <ctype.h>
  • 7.4.1 Character classification functions
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7.4.1 Character classification functions

  • 7.4.1.1 The isalnum function
  • 7.4.1.2 The isalpha function
  • 7.4.1.3 The isblank function
  • 7.4.1.4 The iscntrl function
  • 7.4.1.5 The isdigit function
  • 7.4.1.6 The isgraph function
  • 7.4.1.7 The islower function
  • 7.4.1.8 The isprint function
  • 7.4.1.9 The ispunct function
  • 7.4.1.10 The isspace function
  • 7.4.1.11 The isupper function
  • 7.4.1.12 The isxdigit function

1

The functions in this subclause return nonzero (true) if and only if the value of the argument c conforms to that in the description of the function.

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