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C ctype.h library functions:
All C inbuilt functions which are declared in ctype.h header file are given below. The source code for ctype.h header file is also given below for your reference.
List of inbuilt C functions in ctype.h file:
- “ctype.h” header file support all the below functions in C language. Click on each function name below for detail description and example programs.
| Functions | Description |
| isalpha() | checks whether character is alphabetic |
| isdigit() | checks whether character is digit |
| isalnum() | Checks whether character is alphanumeric |
| isspace() | Checks whether character is space |
| islower() | Checks whether character is lower case |
| isupper() | Checks whether character is upper case |
| isxdigit() | Checks whether character is hexadecimal |
| iscntrl() | Checks whether character is a control character |
| isprint() | Checks whether character is a printable character |
| ispunct() | Checks whether character is a punctuation |
| isgraph() | Checks whether character is a graphical character |
| tolower() | Checks whether character is alphabetic & converts to lower case |
| toupper() | Checks whether character is alphabetic & converts to upper case |
Source code for ctype.h header file:
Please find the source code for ctype.h header file below. This code is taken from DevC++ compiler files for your reference.
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/* * ctype.h * This file has no copyright assigned and is placed in the Public Domain. * This file is a part of the mingw-runtime package. * No warranty is given; refer to the file DISCLAIMER within the package. * * Functions for testing character types and converting characters. * */ #ifndef _CTYPE_H_ #define _CTYPE_H_ /* All the headers include this file. */ #include <_mingw.h> #define __need_wchar_t #define __need_wint_t #ifndef RC_INVOKED #include <stddef.h> #endif /* Not RC_INVOKED */ /* * The following flags are used to tell iswctype and _isctype what character * types you are looking for. */ #define _UPPER 0x0001 #define _LOWER 0x0002 #define _DIGIT 0x0004 #define _SPACE 0x0008 /* HT LF VT FF CR SP */ #define _PUNCT 0x0010 #define _CONTROL 0x0020 #define _BLANK 0x0040 /* this is SP only, not SP and HT as in C99 */ #define _HEX 0x0080 #define _LEADBYTE 0x8000 #define _ALPHA 0x0103 #ifndef RC_INVOKED #ifdef __cplusplus extern "C" { #endif _CRTIMP int __cdecl isalnum(int); _CRTIMP int __cdecl isalpha(int); _CRTIMP int __cdecl iscntrl(int); _CRTIMP int __cdecl isdigit(int); _CRTIMP int __cdecl isgraph(int); _CRTIMP int __cdecl islower(int); _CRTIMP int __cdecl isprint(int); _CRTIMP int __cdecl ispunct(int); _CRTIMP int __cdecl isspace(int); _CRTIMP int __cdecl isupper(int); _CRTIMP int __cdecl isxdigit(int); #ifndef __STRICT_ANSI__ _CRTIMP int __cdecl _isctype (int, int); #endif /* These are the ANSI versions, with correct checking of argument */ _CRTIMP int __cdecl tolower(int); _CRTIMP int __cdecl toupper(int); /* * NOTE: The above are not old name type wrappers, but functions exported * explicitly by MSVCRT/CRTDLL. However, underscored versions are also * exported. */ #ifndef __STRICT_ANSI__ /* * These are the cheap non-std versions: The return values are undefined * if the argument is not ASCII char or is not of appropriate case */ _CRTIMP int __cdecl _tolower(int); _CRTIMP int __cdecl _toupper(int); #endif /* Also defined in stdlib.h */ #ifndef MB_CUR_MAX #ifdef __DECLSPEC_SUPPORTED # ifdef __MSVCRT__ # define MB_CUR_MAX __mb_cur_max __MINGW_IMPORT int __mb_cur_max; # else /* not __MSVCRT */ # define MB_CUR_MAX __mb_cur_max_dll __MINGW_IMPORT int __mb_cur_max_dll; # endif /* not __MSVCRT */ #else /* ! __DECLSPEC_SUPPORTED */ # ifdef __MSVCRT__ extern int* _imp____mbcur_max; # define MB_CUR_MAX (*_imp____mb_cur_max) # else /* not __MSVCRT */ extern int* _imp____mbcur_max_dll; # define MB_CUR_MAX (*_imp____mb_cur_max_dll) # endif /* not __MSVCRT */ #endif /* __DECLSPEC_SUPPORTED */ #endif /* MB_CUR_MAX */ #ifdef __DECLSPEC_SUPPORTED __MINGW_IMPORT unsigned short _ctype[]; # ifdef __MSVCRT__ __MINGW_IMPORT unsigned short* _pctype; # else /* CRTDLL */ __MINGW_IMPORT unsigned short* _pctype_dll; # define _pctype _pctype_dll # endif #else /* __DECLSPEC_SUPPORTED */ extern unsigned short** _imp___ctype; #define _ctype (*_imp___ctype) # ifdef __MSVCRT__ extern unsigned short** _imp___pctype; # define _pctype (*_imp___pctype) # else /* CRTDLL */ extern unsigned short** _imp___pctype_dll; # define _pctype (*_imp___pctype_dll) # endif /* CRTDLL */ #endif /* __DECLSPEC_SUPPORTED */ /* * Use inlines here rather than macros, because macros will upset * C++ usage (eg, ::isalnum), and so usually get undefined * * According to standard for SB chars, these function are defined only * for input values representable by unsigned char or EOF. * Thus, there is no range test. * This reproduces behaviour of MSVCRT.dll lib implemention for SB chars. * * If no MB char support is needed, these can be simplified even * more by command line define -DMB_CUR_MAX=1. The compiler will then * optimise away the constant condition. */ #if ! (defined (__NO_INLINE__) || defined (__NO_CTYPE_INLINES) \ || defined (__STRICT_ANSI__ )) /* use simple lookup if SB locale, else _isctype() */ #define __ISCTYPE(c, mask) (MB_CUR_MAX == 1 ? (_pctype[c] & mask) : _isctype(c, mask)) __CRT_INLINE int __cdecl isalnum(int c) {return __ISCTYPE(c, (_ALPHA|_DIGIT));} __CRT_INLINE int __cdecl isalpha(int c) {return __ISCTYPE(c, _ALPHA);} __CRT_INLINE int __cdecl iscntrl(int c) {return __ISCTYPE(c, _CONTROL);} __CRT_INLINE int __cdecl isdigit(int c) {return __ISCTYPE(c, _DIGIT);} __CRT_INLINE int __cdecl isgraph(int c) {return __ISCTYPE(c, (_PUNCT|_ALPHA|_DIGIT));} __CRT_INLINE int __cdecl islower(int c) {return __ISCTYPE(c, _LOWER);} __CRT_INLINE int __cdecl isprint(int c) {return __ISCTYPE(c, (_BLANK|_PUNCT|_ALPHA|_DIGIT));} __CRT_INLINE int __cdecl ispunct(int c) {return __ISCTYPE(c, _PUNCT);} __CRT_INLINE int __cdecl isspace(int c) {return __ISCTYPE(c, _SPACE);} __CRT_INLINE int __cdecl isupper(int c) {return __ISCTYPE(c, _UPPER);} __CRT_INLINE int __cdecl isxdigit(int c) {return __ISCTYPE(c, _HEX);} /* these reproduce behaviour of lib underscored versions */ __CRT_INLINE int __cdecl _tolower(int c) {return ( c -'A'+'a');} __CRT_INLINE int __cdecl _toupper(int c) {return ( c -'a'+'A');} /* TODO? Is it worth inlining ANSI tolower, toupper? Probably only if we only want C-locale. */ #endif /* _NO_CTYPE_INLINES */ /* Wide character equivalents */ #ifndef WEOF #define WEOF (wchar_t)(0xFFFF) #endif #ifndef _WCTYPE_T_DEFINED typedef wchar_t wctype_t; #define _WCTYPE_T_DEFINED #endif _CRTIMP int __cdecl iswalnum(wint_t); _CRTIMP int __cdecl iswalpha(wint_t); _CRTIMP int __cdecl iswascii(wint_t); _CRTIMP int __cdecl iswcntrl(wint_t); _CRTIMP int __cdecl iswctype(wint_t, wctype_t); _CRTIMP int __cdecl is_wctype(wint_t, wctype_t); /* Obsolete! */ _CRTIMP int __cdecl iswdigit(wint_t); _CRTIMP int __cdecl iswgraph(wint_t); _CRTIMP int __cdecl iswlower(wint_t); _CRTIMP int __cdecl iswprint(wint_t); _CRTIMP int __cdecl iswpunct(wint_t); _CRTIMP int __cdecl iswspace(wint_t); _CRTIMP int __cdecl iswupper(wint_t); _CRTIMP int __cdecl iswxdigit(wint_t); _CRTIMP wchar_t __cdecl towlower(wchar_t); _CRTIMP wchar_t __cdecl towupper(wchar_t); _CRTIMP int __cdecl isleadbyte (int); /* Also in wctype.h */ #if ! (defined (__NO_INLINE__) || defined(__NO_CTYPE_INLINES) \ || defined(__WCTYPE_INLINES_DEFINED)) #define __WCTYPE_INLINES_DEFINED __CRT_INLINE int __cdecl iswalnum(wint_t wc) {return (iswctype(wc,_ALPHA|_DIGIT));} __CRT_INLINE int __cdecl iswalpha(wint_t wc) {return (iswctype(wc,_ALPHA));} __CRT_INLINE int __cdecl iswascii(wint_t wc) {return ((wc & ~0x7F) ==0);} __CRT_INLINE int __cdecl iswcntrl(wint_t wc) {return (iswctype(wc,_CONTROL));} __CRT_INLINE int __cdecl iswdigit(wint_t wc) {return (iswctype(wc,_DIGIT));} __CRT_INLINE int __cdecl iswgraph(wint_t wc) {return (iswctype(wc,_PUNCT|_ALPHA|_DIGIT));} __CRT_INLINE int __cdecl iswlower(wint_t wc) {return (iswctype(wc,_LOWER));} __CRT_INLINE int __cdecl iswprint(wint_t wc) {return (iswctype(wc,_BLANK|_PUNCT|_ALPHA|_DIGIT));} __CRT_INLINE int __cdecl iswpunct(wint_t wc) {return (iswctype(wc,_PUNCT));} __CRT_INLINE int __cdecl iswspace(wint_t wc) {return (iswctype(wc,_SPACE));} __CRT_INLINE int __cdecl iswupper(wint_t wc) {return (iswctype(wc,_UPPER));} __CRT_INLINE int __cdecl iswxdigit(wint_t wc) {return (iswctype(wc,_HEX));} __CRT_INLINE int __cdecl isleadbyte(int c) {return (_pctype[(unsigned char)(c)] & _LEADBYTE);} #endif /* !(defined(__NO_CTYPE_INLINES) || defined(__WCTYPE_INLINES_DEFINED)) */ #ifndef __STRICT_ANSI__ int __cdecl __isascii (int); int __cdecl __toascii (int); int __cdecl __iscsymf (int); /* Valid first character in C symbol */ int __cdecl __iscsym (int); /* Valid character in C symbol (after first) */ #if !(defined (__NO_INLINE__) || defined (__NO_CTYPE_INLINES)) __CRT_INLINE int __cdecl __isascii(int c) {return ((c & ~0x7F) == 0);} __CRT_INLINE int __cdecl __toascii(int c) {return (c & 0x7F);} __CRT_INLINE int __cdecl __iscsymf(int c) {return (isalpha(c) || (c == '_'));} __CRT_INLINE int __cdecl __iscsym(int c) {return (isalnum(c) || (c == '_'));} #endif /* __NO_CTYPE_INLINES */ #ifndef _NO_OLDNAMES /* Not _CRTIMP */ int __cdecl isascii (int); int __cdecl toascii (int); int __cdecl iscsymf (int); int __cdecl iscsym (int); #endif /* Not _NO_OLDNAMES */ #endif /* Not __STRICT_ANSI__ */ #ifdef __cplusplus } #endif #endif /* Not RC_INVOKED */ #endif /* Not _CTYPE_H_ */ |