10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
265 lines
4.4 KiB
Groff
265 lines
4.4 KiB
Groff
.TH STRCAT 3
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.SH NAME
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strcat, strncat, strcmp, strncmp, cistrcmp, cistrncmp, strcpy, strncpy, strecpy, strlen, strchr, strrchr, strpbrk, strspn, strcspn, strtok, strdup, strstr, cistrstr \- string operations
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.ta \w'\fLchar* \fP'u
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.B
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char* strcat(char *s1, char *s2)
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.PP
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.B
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char* strncat(char *s1, char *s2, long n)
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.PP
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.B
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int strcmp(char *s1, char *s2)
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.PP
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.B
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int strncmp(char *s1, char *s2, long n)
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.PP
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.B
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int cistrcmp(char *s1, char *s2)
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.PP
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.B
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int cistrncmp(char *s1, char *s2, long n)
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.PP
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.B
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char* strcpy(char *s1, char *s2)
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.PP
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.B
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char* strecpy(char *s1, char *es1, char *s2)
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.PP
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.B
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char* strncpy(char *s1, char *s2, long n)
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.PP
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.B
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long strlen(char *s)
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.PP
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.B
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char* strchr(char *s, char c)
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.PP
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.B
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char* strrchr(char *s, char c)
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.PP
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.B
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char* strpbrk(char *s1, char *s2)
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.PP
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.B
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long strspn(char *s1, char *s2)
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.PP
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.B
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long strcspn(char *s1, char *s2)
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.PP
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.B
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char* strtok(char *s1, char *s2)
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.PP
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.B
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char* strdup(char *s)
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.PP
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.B
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char* strstr(char *s1, char *s2)
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.PP
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.B
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char* cistrstr(char *s1, char *s2)
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.SH DESCRIPTION
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The arguments
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.I s1, s2
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and
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.I s
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point to null-terminated strings.
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The functions
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.IR strcat ,
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.IR strncat ,
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.IR strcpy ,
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.IR strecpy ,
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and
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.I strncpy
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all alter
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.IR s1 .
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.I Strcat
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and
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.I strcpy
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do not check for overflow of
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the array pointed to by
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.IR s1 .
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.PP
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.I Strcat
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appends a copy of string
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.I s2
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to the end of string
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.IR s1 .
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.I Strncat
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appends at most
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.I n
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bytes.
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Each returns a pointer to the null-terminated result.
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.PP
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.I Strcmp
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compares its arguments and returns an integer
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less than, equal to, or greater than 0,
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according as
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.I s1
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is lexicographically less than, equal to, or
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greater than
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.IR s2 .
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.I Strncmp
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makes the same comparison but examines at most
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.I n
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bytes.
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.I Cistrcmp
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and
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.I cistrncmp
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ignore ASCII case distinctions when comparing strings.
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The comparisons are made with unsigned bytes.
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.PP
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.I Strcpy
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copies string
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.I s2
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to
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.IR s1 ,
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stopping after the null byte has been copied.
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.I Strncpy
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copies exactly
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.I n
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bytes,
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truncating
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.I s2
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or adding
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null bytes to
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.I s1
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if necessary.
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The result will not be null-terminated if the length
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of
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.I s2
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is
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.I n
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or more.
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Each function returns
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.IR s1 .
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.PP
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.I Strecpy
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copies bytes until a null byte has been copied, but writes no bytes beyond
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.IR es1 .
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If any bytes are copied,
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.I s1
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is terminated by a null byte, and a pointer to that byte is returned.
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Otherwise, the original
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.I s1
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is returned.
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.PP
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.I Strlen
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returns the number of bytes in
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.IR s ,
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not including the terminating null byte.
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.PP
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.I Strchr
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.RI ( strrchr )
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returns a pointer to the first (last)
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occurrence of byte
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.I c
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in string
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.IR s ,
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or
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.L 0
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if
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.I c
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does not occur in the string.
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The null byte terminating a string is considered to
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be part of the string.
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.PP
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.I Strpbrk
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returns a pointer to the first occurrence in string
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.I s1
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of any byte from string
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.IR s2 ,
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.L 0
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if no byte from
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.I s2
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exists in
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.IR s1 .
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.PP
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.I Strspn
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.RI ( strcspn )
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returns the length of the initial segment of string
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.I s1
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which consists entirely of bytes from (not from) string
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.IR s2 .
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.PP
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.I Strtok
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considers the string
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.I s1
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to consist of a sequence of zero or more text tokens separated
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by spans of one or more bytes from the separator string
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.IR s2 .
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The first call, with pointer
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.I s1
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specified, returns a pointer to the first byte of the first
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token, and will have written a
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null byte into
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.I s1
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immediately following the returned token.
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The function
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keeps track of its position in the string
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between separate calls; subsequent calls,
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signified by
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.I s1
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being
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.LR 0 ,
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will work through the string
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.I s1
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immediately following that token.
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The separator string
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.I s2
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may be different from call to call.
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When no token remains in
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.IR s1 ,
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.L 0
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is returned.
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.PP
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.I Strdup
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returns a pointer to a distinct copy of the null-terminated string
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.I s
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in space obtained from
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.MR malloc 3
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or
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.L 0
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if no space can be obtained.
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.PP
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.I Strstr
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returns a pointer to the first occurrence of
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.I s2
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as a substring of
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.IR s1 ,
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or 0 if there is none.
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If
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.I s2
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is the null string,
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.I strstr
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returns
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.IR s1 .
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.I Cistrstr
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operates analogously, but ignores ASCII case differences when comparing strings.
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.SH SOURCE
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.B \*9/src/lib9
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.SH SEE ALSO
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.MR memory 3 ,
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.MR rune 3 ,
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.MR runestrcat 3
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.SH BUGS
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These routines know nothing about
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.SM UTF.
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Use the routines in
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.MR rune 3
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as appropriate.
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Note, however, that the definition of
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.SM UTF
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guarantees that
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.I strcmp
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compares
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.SM UTF
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strings correctly.
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.PP
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The outcome of overlapping moves varies among implementations.
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