osd@hou2d.UUCP (Orlando Sotomayor-Diaz) (05/15/86)
From: Orlando Sotomayor-Diaz (The Moderator) <cbosgd!std-c>
mod.std.c Digest Thu, 15 May 86 Volume 16 : Issue 17
Today's Topics:
MORE C standard differences Apr85-Feb86, part 7 of 9
----------------------------------------------------------------------
Date:
From: ihnp4!utzoo!lsuc!msb
Subject: MORE C standard differences Apr85-Feb86, part 7 of 9
To: utzoo!ihnp4!hou2d!osd
# D.11.3.1 The strcat function
The strcat function appends a copy of the string pointed to by s2
* {--> (including the terminating null character)} to the end of
the string pointed to by s1.
# D.11.3.2 The strncat function
The strncat function appends not more than n characters of the
* string pointed to by s2 {--> (not including the terminating null
character)} to the end of the string pointed to by s1.
# D.11.3.2 The strncat function
N--> The number of characters that may end up in the array pointed to
N--> by s1 is strlen(s1)+n+1.
N--> Forward references: the strlen function (#D.11.6.3).
# D.11.4 {Length and -->} Comparison functions
# D.11.4.1 The memcmp function
N--> The contents of "holes" used as padding for purposes of alignment
N--> within structure objects are indeterminate, unless the contents
N--> of the entire object have been set explicitly by the calloc or
N--> memset function. Unions and strings shorter than their allocated
N--> space may also cause problems in comparison.
# D.11.5.1 The memchr function
* The memchr function locates the first occurrence of c {--> (con-
verted to an unsigned char)} in the initial n characters of the
object pointed to by s.
# D.11.5.2 The strchr function
* The strchr function locates the first occurrence of c {--> (con-
verted to a char)} in the string pointed to by s.
Remark: And the same change for strrchr (#D.11.5.5).
# {--> D.11.5.7 The strstr function}
N--> Synopsis
N--> #include <string.h>
N--> char *strstr(const char *s1, const char *s2);
N--> Description
N--> The strstr function locates the first occurrence of the string
N--> pointed to by s2 in the string pointed to by s1.
N--> Returns
N--> The strstr function returns a pointer to the located string, or a
N--> null pointer if the string is not found.
# {D.11.5.7 --> D.11.5.8} The strtok function
<--O The strtok function considers the string pointed to by s1 to con-
<--O sist of a sequence of zero or more text tokens separated by spans
<--O of one or more characters from the string pointed to by s2.
N--> A sequence of calls to the strtok function breaks the string
N--> pointed to by s1 into a sequence of tokens, each of which is del-
N--> imited by a character from the string pointed to by s2. The
N--> first call in the sequence has s1 as its first argument, and is
N--> followed by calls with a null pointer as their first argument.
The separator string pointed to by s2 may be different from call
to call.
N--> The first call in the sequence searches s1 for the first charac-
N--> ter that is NOT contained in the current separator string s2. If
N--> no such character is found, there are no tokens in s1, and the
N--> strtok function returns a null pointer. If such a character is
N--> found, it is the start of the first token.
N--> The strtok function then searches from there for a character that
N--> IS contained in the current separator string. If no such charac-
N--> ter is found, the current token extends to the end of the string
N--> pointed to by s1, and subsequent searches for a token will fail.
N--> If such a character is found, it is overwritten by a null charac-
N--> ter, which terminates the current token. The strtok function
N--> saves a pointer to the following character, from which the next
N--> search for a token will start.
N--> Each subsequent call, with a null pointer as the value of the
N--> first argument, starts searching from the saved pointer and
N--> behaves as described above.
<--O The first call to the strtok function returns a pointer to the
<--O initial character of the first token, and will have written a NUL
<--O character into s1 immediately following the returned token. Each
<--O subsequent call (with the value of the first argument null) re-
<--O turns a pointer to a subsequent token. When no token remains in
<--O s1, the strtok function returns a null pointer.
N--> The strtok function returns a pointer to the first character of a
N--> token, or a null pointer if there is no token.
# {D.11.5.7 --> D.11.5.8} The strtok function
N--> Example
N--> #include <string.h>
N--> static char str[] = "?a???b,,,#c";
N--> char *t;
N--> t = strtok(str, "?"); /* t points to the token "a" */
N--> t = strtok(NULL, ","); /* t points to the token "??b" */
N--> t = strtok(NULL, "#,"); /* t points to the token "c" */
N--> t = strtok(NULL, "?"); /* t is a null pointer */
# {--> D.11.6 Miscellaneous functions}
# {D.11.2.2 --> D.11.6.1} The memset function
* The memset function copies the value of c ({cast --> converted}
* to an unsigned char) into each of the first n {bytes --> charac-
ters} of the object pointed to by s.
# {--> D.11.6.2 The strerror function}
N--> Synopsis
N--> #include <string.h>
N--> char *strerror(int errnum);
N--> Description
N--> The strerror function maps the error number in errnum to an error
N--> message string.
N--> Returns
N--> The strerror function returns a pointer to the string, the con-
N--> tents of which are implementation-defined. The array pointed to
N--> is not modifiable by the program, but may be overwritten by a
N--> subsequent call to the strerror function.
# {D.11.4.3 --> D.11.6.3} the strlen function
The strlen function computes the length of the string pointed to
* by s {, not counting the terminating NUL character -->}. ...
* The strlen function returns the number of {initial -->} charac-
* ters {--> that precede the terminating null character}.
# D.12.1 Components of time
Many functions deal with a "calendar time" that represents the
* current date {--> (according to the Gregorian calendar)} and
time.
# D.12.1 Components of time
* int tm_mon; /* {month of the year -->
months since January} - [0, 11] */
...
* int tm_yday; /* {day of the year -->
days since January 1} - [0, 365] */
------------------------------
End of mod.std.c Digest - Thu, 15 May 86 13:32:04 EDT
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