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HP C
Run-Time Library Reference Manual for
OpenVMS Systems
2.6 Program Examples
This section gives some program examples that show how the I/O
functions can be used in applications.
Example 2-1 shows the
printf
function.
| Example 2-1 Output of the Conversion
Specifications |
/* CHAP_2_OUT_CONV.C */
/* This program uses the printf function to print the */
/* various conversion specifications and their effect */
/* on the output. */
/* Include the proper header files in case printf has */
/* to return EOF. */
#include <stdlib.h>
#include <stdio.h>
#include <wchar.h>
#define WIDE_STR_SIZE 20
main()
{
double val = 123345.5;
char c = 'C';
int i = -1500000000;
char *s = "thomasina";
wchar_t wc;
wchar_t ws[WIDE_STR_SIZE];
/* Produce a wide character and a wide character string */
if (mbtowc(&wc, "W", 1) == -1) {
perror("mbtowc");
exit(EXIT_FAILURE);
}
if (mbstowcs(ws, "THOMASINA", WIDE_STR_SIZE) == -1) {
perror("mbstowcs");
exit(EXIT_FAILURE);
}
/* Print the specification code, a colon, two tabs, and the */
/* formatted output value delimited by the angle bracket */
/* characters (<>). */
printf("%%9.4f:\t\t<%9.4f>\n", val);
printf("%%9f:\t\t<%9f>\n", val);
printf("%%9.0f:\t\t<%9.0f>\n", val);
printf("%%-9.0f:\t\t<%-9.0f>\n\n", val);
printf("%%11.6e:\t\t<%11.6e>\n", val);
printf("%%11e:\t\t<%11e>\n", val);
printf("%%11.0e:\t\t<%11.0e>\n", val);
printf("%%-11.0e:\t\t<%-11.0e>\n\n", val);
printf("%%11g:\t\t<%11g>\n", val);
printf("%%9g:\t\t<%9g>\n\n", val);
printf("%%d:\t\t<%d>\n", c);
printf("%%c:\t\t<%c>\n", c);
printf("%%o:\t\t<%o>\n", c);
printf("%%x:\t\t<%x>\n\n", c);
printf("%%d:\t\t<%d>\n", i);
printf("%%u:\t\t<%u>\n", i);
printf("%%x:\t\t<%x>\n\n", i);
printf("%%s:\t\t<%s>\n", s);
printf("%%-9.6s:\t\t<%-9.6s>\n", s);
printf("%%-*.*s:\t\t<%-*.*s>\n", 9, 5, s);
printf("%%6.0s:\t\t<%6.0s>\n\n", s);
printf("%%C:\t\t<%C>\n", wc);
printf("%%S:\t\t<%S>\n", ws);
printf("%%-9.6S:\t\t<%-9.6S>\n", ws);
printf("%%-*.*S:\t\t<%-*.*S>\n", 9, 5, ws);
printf("%%6.0S:\t\t<%6.0S>\n\n", ws);
}
|
Running Example 2-1 produces the following output:
$ RUN EXAMPLE
%9.4f: <123345.5000>
%9f: <123345.500000>
%9.0f: < 123346>
%-9.0f: <123346 >
%11.6e: <1.233455e+05>
%11e: <1.233455e+05>
%11.0e: < 1e+05>
%-11.0e: <1e+05 >
%11g: < 123346>
%9g: < 123346>
%d: <67>
%c: <C>
%o: <103>
%x: <43>
%d: <-1500000000>
%u: <2794967296>
%x: <a697d100>
%s: <thomasina>
%-9.6s: <thomas >
%-*.*s: <thoma >
%6.0s: < >
%C: <W>
%S: <THOMASINA>
%-9.6S: <THOMAS >
%-*.*S: <THOMA >
%6.0S: < >
$
|
Example 2-2 shows the use of the
fopen
,
ftell
,
sprintf
,
fputs
,
fseek
,
fgets
, and
fclose
functions.
| Example 2-2 Using the Standard I/O
Functions |
/* CHAP_2_STDIO.C */
/* This program establishes a file pointer, writes lines from */
/* a buffer to the file, moves the file pointer to the second */
/* record, copies the record to the buffer, and then prints */
/* the buffer to the screen. */
#include <stdio.h>
#include <stdlib.h>
main()
{
char buffer[32];
int i,
pos;
FILE *fptr;
/* Set file pointer. */
fptr = fopen("data.dat", "w+");
if (fptr == NULL) {
perror("fopen");
exit(EXIT_FAILURE);
}
for (i = 1; i < 5; i++) {
if (i == 2) /* Get position of record 2. */
pos = ftell(fptr);
/* Print a line to the buffer. */
sprintf(buffer, "test data line %d\n", i);
/* Print buffer to the record. */
fputs(buffer, fptr);
}
/* Go to record number 2. */
if (fseek(fptr, pos, 0) < 0) {
perror("fseek"); /* Exit on fseek error. */
exit(EXIT_FAILURE);
}
/* Read record 2 in the buffer. */
if (fgets(buffer, 32, fptr) == NULL) {
perror("fgets"); /* Exit on fgets error. */
exit(EXIT_FAILURE);
}
/* Print the buffer. */
printf("Data in record 2 is: %s", buffer);
fclose(fptr); /* Close the file. */
}
|
Running Example 2-2 produces the following result:
$ RUN EXAMPLE
Data in record 2 is: test data line 2
|
The output to DATA.DAT from Example 2-2 is:
test data line 1
test data line 2
test data line 3
test data line 4
|
| Example 2-3 Using Wide Character I/O
Functions |
/* CHAP_2_WC_IO.C */
/* This program establishes a file pointer, writes lines from */
/* a buffer to the file using wide-character codes, moves the */
/* file pointer to the second record, copies the record to the */
/* wide-character buffer, and then prints the buffer to the */
/* screen. */
#include <stdio.h>
#include <stdlib.h>
#include <wchar.h>
main()
{
char flat_buffer[32];
wchar_t wide_buffer[32];
wchar_t format[32];
int i,
pos;
FILE *fptr;
/* Set file pointer. */
fptr = fopen("data.dat", "w+");
if (fptr == NULL) {
perror("fopen");
exit(EXIT_FAILURE);
}
for (i = 1; i < 5; i++) {
if (i == 2) /* Get position of record 2. */
pos = ftell(fptr);
/* Print a line to the buffer. */
sprintf(flat_buffer, "test data line %d\n", i);
if (mbstowcs(wide_buffer, flat_buffer, 32) == -1) {
perror("mbstowcs");
exit(EXIT_FAILURE);
}
/* Print buffer to the record. */
fputws(wide_buffer, fptr);
}
/* Go to record number 2. */
if (fseek(fptr, pos, 0) < 0) {
perror("fseek"); /* Exit on fseek error. */
exit(EXIT_FAILURE);
}
/* Put record 2 in the buffer. */
if (fgetws(wide_buffer, 32, fptr) == NULL) {
perror("fgetws"); /* Exit on fgets error. */
exit(EXIT_FAILURE);
}
/* Print the buffer. */
printf("Data in record 2 is: %S", wide_buffer);
fclose(fptr); /* Close the file. */
}
|
Running Example 2-3 produces the following result:
$ RUN EXAMPLE
Data in record 2 is: test data line 2
|
The output to DATA.DAT from Example 2-3 is:
test data line 1
test data line 2
test data line 3
test data line 4
|
Example 2-4 shows the use of both a file pointer and a file
descriptor to access a single file.
| Example 2-4 I/O Using File Descriptors and
Pointers |
/* CHAP_2_FILE_DIS_AND_POINTER.C */
/* The following example creates a file with variable-length */
/* records (rfm=var) and the carriage-return attribute (rat=cr).*/
/* */
/* The program uses creat to create and open the file, and */
/* fdopen to associate the file descriptor with a file pointer. */
/* After using the fdopen function, the file must be referenced */
/* using the Standard I/O functions. */
#include <unixio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define ERROR 0
#define ERROR1 -1
#define BUFFSIZE 132
main()
{
char buffer[BUFFSIZE];
int fildes;
FILE *fp;
if ((fildes = creat("data.dat", 0, "rat=cr",
"rfm=var")) == ERROR1) {
perror("DATA.DAT: creat() failed\n");
exit(EXIT_FAILURE);
}
if ((fp = fdopen(fildes, "w")) == NULL) {
perror("DATA.DAT: fdopen() failed\n");
exit(EXIT_FAILURE);
}
while (fgets(buffer, BUFFSIZE, stdin) != NULL)
if (fwrite(buffer, strlen(buffer), 1, fp) == ERROR) {
perror("DATA.DAT: fwrite() failed\n");
exit(EXIT_FAILURE);
}
if (fclose(fp) == EOF) {
perror("DATA.DAT: fclose() failed\n");
exit(EXIT_FAILURE);
}
}
|
Chapter 3
Character, String, and Argument-List Functions
Table 3-1 describes the character, string, and argument-list
functions in the HP C Run-Time Library (RTL). Although further discussion follows in
this chapter, 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.
|
|
iswctype
|
Returns a nonzero integer if its argument has the specified property.
|
|
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.
|
|
wcstombs
|
Converts a sequence of wide-character codes corresponding to multibyte
characters to a sequence of multibyte characters.
|
|
wctob
|
Determines if a wide character corresponds to a single-byte multibyte
character and returns its multibyte character representation.
|
|
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
.
|
|
wctype
|
Converts a valid character class defined for the current locale to an
object of type
wctype_t
.
|
| 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, I64)
|
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 returns 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, I64)
|
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, I64)
|
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
(ALPHA 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.
|
|
|
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