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Compaq C

Compaq C
Run-Time Library Reference Manual for OpenVMS Systems


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Chapter 3
Character, String, and Argument-List Functions

Table 3-1 describes the character, string, and argument-list functions in the Compaq C Run-Time Library (RTL). Although further discussion follows, see the Reference Section for more detailed information on each function.

Table 3-1 Character, String, and Argument-List Functions
Function Description
Character Classification
isalnum , iswalnum Returns a nonzero integer if its argument is one of the alphanumeric characters in the current locale.
isalpha , iswalpha Returns a nonzero integer if its argument is one of the alphabetic characters in the current locale.
isascii Returns a nonzero integer if its argument is any ASCII character.
iscntrl , iswcntrl Returns a nonzero integer if its argument is a control character in the current locale.
isdigit , iswdigit Returns a nonzero integer if its argument is a digit character in the current locale.
isgraph , iswgraph Returns a nonzero integer if its argument is a graphic character in the current locale.
islower , iswlower Returns a nonzero integer if its argument is a lowercase character in the current locale.
isprint , iswprint Returns a nonzero integer if its argument is a printing character in the current locale.
ispunct , iswpunct Returns a nonzero integer if its argument is a punctuation character in the current locale.
isspace , iswspace Returns a nonzero integer if its argument is a white space character in the current locale.
isupper , iswupper Returns a nonzero integer if its argument is an uppercase character in the current locale.
isxdigit , iswxdigit Returns a nonzero integer if its argument is a hexadecimal digit (0 to 9, A to F, or a to f).
Character Conversion
btowc Converts a one-byte multibyte character to a wide character in the initial shift state.
ecvt, fcvt, gcvt Converts an argument to a null-terminated string of ASCII digits and return the address of the string.
index, rindex Searches for a character in a string.
mblen , mbrlen Determines the number of bytes in a multibyte character.
mbsinit Determines whether an mbstate_t object decribes an initial conversion state.
mbstowcs Converts a sequence of multibyte characters into a sequence of corresponding codes.
toascii Converts its argument, an 8-bit ASCII character, to a 7-bit ASCII character.
tolower, _tolower, towlower Converts its argument, an uppercase character, to lowercase.
toupper, _toupper, towupper Converts its argument, a lowercase character, to uppercase.
towctrans Maps one wide character to another according to a specified mapping descriptor.
wctob Determines if a wide character corresponds to a single-byte multibyte character and returns its multibyte character representation.
wcstombs Converts a sequence of wide-character codes corresponding to multibyte characters to a sequence of multibyte characters.
wctomb Converts a wide character to its multibyte character representation.
wctrans Returns the description of a mapping, corresponding to specified property, that can be later used in a call to towctrans .
String Manipulation
atof Converts a given string to a double-precision number.
atoi, atol Converts a given string of ASCII characters to the appropriate numeric values.
atoll, atoq (ALPHA ONLY) Converts a given string of ASCII characters to an __int64 .
basename Returns the last component of a path name.
dirname Reports the parent directory name of a file path name.
strcat, strncat, wcscat, wcsncat Appends one string to the end of another string.
strchr, strrchr, wcschr, wcsrchr Returns the address of the first or last occurrence of a given character in a null-terminated string.
strcmp, strncmp, strcoll, wcscmp, wcsncmp, wcscoll Compares two character strings and return a negative, zero, or positive integer indicating that the values of the individual characters in the first string are less than, equal to, or greater than the values in the second string.
strcpy, strncpy, wcscpy, wcsncpy Copies all or part of one string into another.
strxfrm, wcsxfrm Transforms a multibyte string to another string ready for comparisons using the strcmp or wcscmp function.
strcspn, wcscspn Searches a string for a character that is in a specified set of characters.
strlen, wcslen Returns the length of a string of characters. The returned length does not include the terminating null character (\0).
strpbrk, wcspbrk Searches a string for the occurrence of one of a specified set of characters.
strspn, wcsspn Searches a string for the occurrence of a character that is not in a specified set of characters.
strstr, wcswcs Searches a string for the first occurrence of a specified set of characters.
strtod, wcstod Converts a given string to a double-precision number.
strtok, wcstok Locates text tokens in a given string.
strtol, wcstol Converts the initial portion of a string to a signed long integer.
strtoll, strtoq (ALPHA ONLY) Converts the initial portion of a string to signed __int64 .
strtoul, wcstoul Converts the initial portion of `a string to an unsigned long integer.
strtoull, strtouq (ALPHA ONLY) Converts the initial portion of the string pointed to by the pointer to the character string to an unsigned __int64 .
String Handling---Accessing Binary Data
bcmp Compares byte strings.
bcopy Copies byte strings.
bzero Copies nulls into byte strings.
memchr, wmemchr Locates the first occurrence of the specified byte within the initial length of the object to be searched.
memcmp, wmemcmp Compares two objects byte by byte.
memcpy, memmove, wmemcpy, wmemmove Copies a specified number of bytes from one object to another.
memset, wmemset Sets a specified number of bytes in a given object to a given value.
Argument-List Handling---Accessing a Variable-Length Argument List
va_arg Returns the next item in the argument list.
va_count Returns the number of longwords (VAX ONLY) or quadwords (VAX ONLY) in the argument list.
va_end Finishes the va_start session.
va_start, va_start_1 Initializes a variable to the beginning of the argument list.
vfprintf, vprintf, vsprintf Prints formatted output based on an argument list.

3.1 Character-Classification Functions

The character-classification functions take a single argument on which they perform a logical operation. The argument can have any value; it does not have to be an ASCII character. The isascii function determines if the argument is an ASCII character (0 through 177 octal). The other functions determine whether the argument is a particular type of ASCII character, such as a graphic character or digit. The isw* functions test wide characters. Character-classification information is in the LC_CTYPE category of the program's current locale.

For all functions, a positive return value indicates TRUE. A return value of 0 indicates FALSE.

To briefly reference the character-classification functions in a subsequent table, each function is assigned a number, as shown in Table 3-2.

Table 3-2 Character-Classification Functions
Function
Number
Function Function
Number
Function
1 isalnum 7 islower
2 isalpha 8 isprint
3 isascii 9 ispunct
4 iscntrl 10 isspace
5 isdigit 11 isupper
6 isgraph 12 isxdigit

Table 3-3 lists the numbers of the functions (as assigned in Table 3-2) that return the value TRUE for each of the given ASCII characters. The numeric code represents the octal value of each of the ASCII characters.

Table 3-3 ASCII Characters and the Character-Classification Functions
ASCII
Values
Function
Numbers
ASCII
Values
Function
Numbers
NUL 00 3,4 @ 100 3,6,8,9
SOH 01 3,4 A 101 1,2,3,6,8,11,12
STX 02 3,4 B 102 1,2,3,6,8,11,12
ETX 03 3,4 C 103 1,2,3,6,8,11,12
EOT 04 3,4 D 104 1,2,3,6,8,11,12
ENQ 05 3,4 E 105 1,2,3,6,8,11,12
ACK 06 3,4 F 106 1,2,3,6,8,11,12
BEL 07 3,4 G 107 1,2,3,6,8,11
BS 10 3,4 H 110 1,2,3,6,8,11
HT 11 3,4,10 I 111 1,2,3,6,8,11
LF 12 3,4,10 J 112 1,2,3,6,8,11
VT 13 3,4,10 K 113 1,2,3,6,8,11
FF 14 3,4,10 L 114 1,2,3,6,8,11
CR 15 3,4,10 M 115 1,2,3,6,8,11
SO 16 3,4 N 116 1,2,3,6,8,11
SI 17 3,4 O 117 1,2,3,6,8,11
       
DLE 20 3,4 P 120 1,2,3,6,8,11
DC1 21 3,4 Q 121 1,2,3,6,8,11
DC2 22 3,4 R 122 1,2,3,6,8,11
DC3 23 3,4 S 123 1,2,3,6,8,11
DC4 24 3,4 T 124 1,2,3,6,8,11
NAK 25 3,4 U 125 1,2,3,6,8,11
SYN 26 3,4 V 126 1,2,3,6,8,11
ETB 27 3,4 W 127 1,2,3,6,8,11
       
CAN 30 3,4 X 130 1,2,3,6,8,11
EM 31 3,4 Y 131 1,2,3,6,8,11
SUB 32 3,4 Z 132 1,2,3,6,8,11
ESC 33 3,4 [ 133 3,6,8,9
FS 34 3,4 \ 134 3,6,8,9
GS 35 3,4 ] 135 3,6,8,9
RS 36 3,4 ^ 136 3,6,8,9
US 37 3,4 -- 137 3,6,8,9
       
SP 40 3,8,10 ?` 140 3,6,8,9
! 41 3,6,8,9 a 141 1,2,3,6,7,8,12
" 42 3,6,8,9 b 142 1,2,3,6,7,8,12
# 43 3,6,8,9 c 143 1,2,3,6,7,8,12
$ 44 3,6,8,9 d 144 1,2,3,6,7,8,12
% 45 3,6,8,9 e 145 1,2,3,6,7,8,12
& 46 3,6,8,9 f 146 1,2,3,6,7,8,12
' 47 3,6,8,9 g 147 1,2,3,6,7,8
       
( 50 3,6,8,9 h 150 1,2,3,6,7,8
) 51 3,6,8,9 i 151 1,2,3,6,7,8
* 52 3,6,8,9 j 152 1,2,3,6,7,8
+ 53 3,6,8,9 k 153 1,2,3,6,7,8
' 54 3,6,8,9 l 154 1,2,3,6,7,8
- 55 3,6,8,9 m 155 1,2,3,6,7,8
?. 56 3,6,8,9 n 156 1,2,3,6,7,8
/ 57 3,6,8,9 o 157 1,2,3,6,7,8
       
0 60 1,3,5,6,8,12 p 160 1,2,3,6,7,8
1 61 1,3,5,6,8,12 q 161 1,2,3,6,7,8
2 62 1,3,5,6,8,12 r 162 1,2,3,6,7,8
3 63 1,3,5,6,8,12 s 163 1,2,3,6,7,8
4 64 1,3,5,6,8,12 t 164 1,2,3,6,7,8
5 65 1,3,5,6,8,12 u 165 1,2,3,6,7,8
6 66 1,3,5,6,8,12 v 166 1,2,3,6,7,8
7 67 1,3,5,6,8,12 w 167 1,2,3,6,7,8
       
8 70 1,3,5,6,8,12 x 170 1,2,3,5,6,8
9 71 1,3,5,6,8,12 y 171 1,2,3,5,6,8
: 72 3,6,8,9 z 172 1,2,3,5,6,8
; 73 3,6,8,9 { 173 3,6,8,9
< 74 3,6,8,9 | 174 3,6,8,9
= 75 3,6,8,9 } 175 3,6,8,9
> 76 3,6,8,9 ?~ 176 3,6,8,9
? 77 3,6,8,9 DEL 177 3,4

Example 3-1 shows how the character-classification functions are used.

Example 3-1 Character-Classification Functions

/*       CHAP_3_CHARCLASS.C                                     */ 
 
/* This example uses the isalpha, isdigit, and isspace          */ 
/* functions to count the number of occurrences of letters,     */ 
/* digits, and white-space characters entered through the       */ 
/* standard input (stdin).                                      */ 
 
#include <ctype.h> 
#include <stdio.h> 
#include <stdlib.h> 
 
main() 
{ 
    char c; 
    int i = 0, 
        j = 0, 
        k = 0; 
 
    while ((c = getchar()) != EOF) { 
        if (isalpha(c)) 
            i++; 
        if (isdigit(c)) 
            j++; 
        if (isspace(c)) 
            k++; 
    } 
 
    printf("Number of letters: %d\n", i); 
    printf("Number of digits:  %d\n", j); 
    printf("Number of spaces:  %d\n", k); 
} 


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