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Returns the number of bytes in a string.
#include <string.h>size_t strnlen (const char *s, size_t n);
s
Pointer to the string.n
The maximum number of characters to examine.
The strnlen function returns the number of bytes in the string pointed to by s. The string length value does not include the terminating null character. The strnlen function counts bytes until the first null byte or until n bytes have been examined.
n The length of the string.
Searches a string for the occurrence of one of a specified set of characters.
#include <string.h>Function Variants The strpbrk function has variants named _strpbrk32 and _strpbrk64 for use with 32-bit and 64-bit pointer sizes, respectively. See Section 1.10 for more information on using pointer-size-specific functions.char *strpbrk (const char *str, const char *charset);
str
A pointer to a character string. If this character string is a null string, 0 is returned.charset
A pointer to a character string containing the set of characters for which the function will search.
The strpbrk function scans the characters in the string, stops when it encounters a character found in charset, and returns the address of the first character in the string that appears in the character set.
x The address of the first character in the string that is in the set. NULL Indicates that no character is in the set.
Converts a character string into date and time values that are stored in a tm structure. Conversion is controlled by a format string.
#include <time.h>Function Variants The strptime function has variants named _strptime32 and _strptime64 for use with 32-bit and 64-bit pointer sizes, respectively. See Section 1.10 for more information on using pointer-size-specific functions.char *strptime (const char *buf, const char *format, struct tm *timeptr);
buf
A pointer to the character string to convert.format
A pointer to the string that defines how the input string is converted.timeptr
A pointer to the local time structure. The tm structure is defined in the <time.h> header file.
The strptime function converts the string pointed to by buf into values that are stored in the structure pointed to by timeptr. The string pointed to by format defines how the conversion is performed.The strptime function modifies only those fields in the tm structure that have corresponding conversion specifications in the format. In particular, strptime never sets the tm_isdst member of the tm structure.
The format string consists of zero or more directives. A directive is composed of one of the following:
- One or more white-space characters (as defined by the isspace function). This directive causes the function to read input up to the first character that is not a white-space character.
- Any character other than the percent character (%) or a white-space character. This directive causes the function to read the next character. The character read must be the same as the character that comprises the directive. If the character is different, the function fails.
- A conversion specification. A conversion specification defines how characters in the input string are interpreted as values that are then stored in the tm structure. A conversion specification consists of a percent (%) character followed by a conversion specifier. Table REF-9 lists the valid conversion specifications.
The strptime function uses fields in the LC_TIME category of the program's current locale to provide a value.
Note
To be compliant with X/Open CAE Specification System Interfaces and Headers Issue 5 (commonly known as XPG5), the strptime function processes the "%y" directive differently than in previous versions of the HP C RTL.
With Version 6.4 and higher of the C compiler, for a two-digit year within the century if no century is specified, "%y" directive values range from:
- 69 to 99 refer to years in the twentieth century (1969 to 1999 inclusive)
- 00 to 68 refer to years in the twenty-first century (2000 to 2068 inclusive)
In previous (XPG4-compliant) versions of the HP C RTL, strptime interpreted a two-digit year with no century specified as a year within the twentieth century.
The XPG5-compliant strptime is now the default version in the HP C RTL.
To obtain the old, XPG4-compliant strptime function behavior, specify one of the following:
- Define the DECC$XPG4_STRPTIME logical name as follows:
$ DEFINE DECC$XPG4_STRPTIME ENABLE
or:- Call the XPG4 strptime directly as the function decc$strptime_xpg4 .
To return to using the XPG5 strptime version, DEASSIGN the DECC$XPG4_STRPTIME logical name:
$ DEASSIGN DECC$XPG4_STRPTIME
Table REF-9 strptime Conversion Specifications Specification Replaced by %a The weekday name. This is either the abbreviated or the full name. %A Same as %a . %b The month name. This is either the abbreviated or the full name. %B Same as %b . %c The date and time using the locale's date format. %Ec The locale's alternative date and time representation. %C The century number (the year divided by 100 and truncated to an integer) as a decimal number (00 -- 99). Leading zeros are permitted. %EC The name of the base year (period) in the locale's alternative representation. %d The day of the month as a decimal number (01 -- 31). Leading zeros are permitted. %Od The day of the month using the locale's alternative numeric symbols. %D Same as %m/%d/%y . %e Same as %d . %Oe The date of the month using the locale's alternative numeric symbols. %h Same as %b . %H The hour (24-hour clock) as a decimal number (00 -- 23). Leading zeros are permitted. %OH The hour (24-hour clock) using the locale's alternative numeric symbols. %I The hour (12-hour clock) as a decimal number (01 -- 12). Leading zeros are permitted. %OI The hour (12-hour clock) using the locale's alternative numeric symbols. %j The day of the year as a decimal number (001 -- 366). %m The month as a decimal number (01 -- 12). Leading zeros are permitted. %Om The month using the locale's alternative numeric symbols. %M The minute as a decimal number (00 -- 59). Leading zeros are permitted. %OM The minutes using the locale's alternative numeric symbols. %n Any white-space character. %p The locale's equivalent of the AM/PM designations associated with a 12-hour clock. %r The time in AM/PM notation ( %I:%M:%S %p ). %R The time in 24-hour notation ( %H:%M ). %S The second as a decimal number (00 -- 61). Leading zeros are permitted. %OS The seconds using the locale's alternative numeric symbols. %t Any white-space character. %T The time ( %H:%M:%S ). %U The week number of the year (the first Sunday as the first day of week 1) as a decimal number (00 -- 53). Leading zeros are permitted. %OU The week number of the year (Sunday as the first day of the week) using the locale's alternative numeric symbols. %w The weekday as a decimal number (0 [Sunday] -- 6). Leading zeros are permitted. %Ow The weekday as a number (Sunday=0) using the locale's alternative numeric symbols. %W The week number of the year (the first Monday as the first day of week 1) as a decimal number (00 -- 53). Leading zeros are permitted. %OW The week number of the year (Monday as the first day of the week) using the locale's alternative numeric symbols. %x The locale's appropriate date representation. %Ex The locale's alternative date representation. %EX The locale's alternative time representation. %X The locale's appropriate time representation. %y The year without century as a decimal number (00 -- 99). %Ey The offset from the base year ( %EC ) in the locale's alternative representation. %Oy The year without the century using the locale's alternative numeric symbols. %Y The year with century as a decimal number. %EY The locale's full alternative year representation. %% Literal % character.
x A pointer to the character following the last character parsed. NULL Indicates that an error occurred. The contents of the tm structure are undefined.
#include <string.h> #include <stdlib.h> #include <stdio.h> #include <time.h> #include <locale.h> #include <errno.h> #define NUM_OF_DATES 7 #define BUF_SIZE 256 /* This program takes a number of date and time strings and */ /* converts them into tm structs using strptime(). These tm */ /* structs are then passed to strftime() which will reverse the */ /* process. The resulting strings are then compared with the */ /* originals and if a difference is found then an error is */ /* displayed. */ main() { int count, i; char buffer[BUF_SIZE]; char *ret_val; struct tm time_struct; char dates[NUM_OF_DATES][BUF_SIZE] = { "Thursday 01 January 1970 00:08:20", "Tuesday 29 February 1972 08:26:40", "Tuesday 31 December 1991 23:59:59", "Wednesday 01 January 1992 00:00:00", "Sunday 03 May 1992 13:33:20", "Monday 04 May 1992 17:20:00", "Friday 15 May 1992 03:20:00"}; for (i = 0; i < NUM_OF_DATES; i++) { /* Convert to a tm structure */ ret_val = strptime(dates[i], "%A %d %B %Y %T", &time_struct); /* Check the return value */ if (ret_val == (char *) NULL) { perror("strptime"); exit(EXIT_FAILURE); } /* Convert the time structure back to a formatted string */ count = strftime(buffer, BUF_SIZE, "%A %d %B %Y %T",&time_struct); /* Check the return value */ if (count == 0) { perror("strftime"); exit(EXIT_FAILURE); } /* Check the result */ if (strcmp(buffer, dates[i]) != 0) { printf("Error: Converted string differs from the original\n"); } else { printf("Successfully converted <%s>\n", dates[i]); } } }
Running the example program produces the following result:
Successfully converted <Thursday 01 January 1970 00:08:20> Successfully converted <Tuesday 29 February 1972 08:26:40> Successfully converted <Tuesday 31 December 1991 23:59:59> Successfully converted <Wednesday 01 January 1992 00:00:00> Successfully converted <Sunday 03 May 1992 13:33:20> Successfully converted <Monday 04 May 1992 17:20:00> Successfully converted <Friday 15 May 1992 03:20:00> |
Returns the address of the last occurrence of a given character in a null-terminated string. The terminating null character is considered to be part of the string.
#include <string.h>Function Variants The strrchr function has variants named _strrchr32 and _strrchr64 for use with 32-bit and 64-bit pointer sizes, respectively. See Section 1.10 for more information on using pointer-size-specific functions.char *strrchr (const char *str, int character);
str
A pointer to a null-terminated character string.character
An object of type int .
See strchr .
x The address of the last occurrence of the specified character. NULL Indicates that the character does not occur in the string.
Separates strings.
#include <string.h>Function Variants The strsep function has variants named _strsep32 and _strsep64 for use with 32-bit and 64-bit pointer sizes, respectively. See Section 1.10 for more information on using pointer-size-specific functions.char *strsep (char **stringp, char *delim);
stringp
A pointer to a pointer to a character string.delim
A pointer to a string containing characters to be used as delimiters.
The strsep function locates in stringp, the first occurrence of any character in delim (or the terminating '\0' character) and replaces it with a '\0'. The location of the next character after the delimiter character (or NULL, if the end of the string is reached) is stored in the stringp argument. The original value of the stringp argument is returned.You can detect an "empty" field; one caused by two adjacent delimiter characters, by comparing the location referenced by the pointer returned in the stringp argument to '\0'.
The stringp argument is initially NULL, strsep returns NULL.
x The address of the string pointed to by stringp. NULL Indicates that stringp is NULL.
The following example uses strsep to parse a string, containing token delimited by white space, into an argument vector:
char **ap, **argv[10], *inputstring; for (ap = argv; (*ap = strsep(&inputstring, " \t")) != NULL;) if (**ap != '\0') ++ap;
Returns the length of the prefix of a string that consists entirely of characters from a set of characters.
#include <string.h>size_t strspn (const char *str, const char *charset);
str
A pointer to a character string. If this string is a null string, 0 is returned.charset
A pointer to a character string containing the characters for which the function will search.
The strspn function scans the characters in the string, stops when it encounters a character not found in charset, and returns the length of the string's initial segment formed by characters found in charset.
x The length of the segment.
Locates the first occurrence in the string pointed to by s1 of the sequence of characters in the string pointed to by s2.
#include <string.h>Function Variants The strstr function has variants named _strstr32 and _strstr64 for use with 32-bit and 64-bit pointer sizes, respectively. See Section 1.10 for more information on using pointer-size-specific functions.char *strstr (const char *s1, const char *s2);
s1, s2
Pointers to character strings.
Pointer A pointer to the located string. NULL Indicates that the string was not found.
#include <stdlib.h> #include <stdio.h> #include <string.h> main() { static char lookin[]="that this is a test was at the end"; putchar('\n'); printf("String: %s\n", &lookin[0] ); putchar('\n'); printf("Addr: %s\n", &lookin[0] ); printf("this: %s\n", strstr( &lookin[0] ,"this") ); printf("that: %s\n", strstr( &lookin[0] , "that" ) ); printf("NULL: %s\n", strstr( &lookin[0], "" ) ); printf("was: %s\n", strstr( &lookin[0], "was" ) ); printf("at: %s\n", strstr( &lookin[0], "at" ) ); printf("the end: %s\n", strstr( &lookin[0], "the end") ); putchar('\n'); exit(0); }
This example produces the following results:
$ RUN STRSTR_EXAMPLE String: that this is a test was at the end Addr: that this is a test was at the end this: this is a test was at the end that: that this is a test was at the end NULL: that this is a test was at the end was: was at the end at: at this is a test was at the end the end: the end $ |
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