.TH STRCAT 2.SH NAMEstrcat, strncat, strcmp, strncmp, cistrcmp, cistrncmp, strcpy, strncpy, strecpy, strlen, strchr, strrchr, strpbrk, strspn, strcspn, strtok, strdup, strstr, cistrstr \- string operations.SH SYNOPSIS.B #include <u.h>.br.B #include <libc.h>.PP.ta \w'\fLchar* \fP'u.Bchar*	strcat(char *s1, char *s2).PP.Bchar*	strncat(char *s1, char *s2, long n).PP.Bint	strcmp(char *s1, char *s2).PP.Bint	strncmp(char *s1, char *s2, long n).PP.Bint	cistrcmp(char *s1, char *s2).PP.Bint	cistrncmp(char *s1, char *s2, long n).PP.Bchar*	strcpy(char *s1, char *s2).PP.Bchar*	strecpy(char *s1, char *es1, char *s2).PP.Bchar*	strncpy(char *s1, char *s2, long n).PP.Blong	strlen(char *s).PP.Bchar*	strchr(char *s, char c).PP.Bchar*	strrchr(char *s, char c).PP.Bchar*	strpbrk(char *s1, char *s2).PP.Blong	strspn(char *s1, char *s2).PP.Blong	strcspn(char *s1, char *s2).PP.Bchar*	strtok(char *s1, char *s2).PP.Bchar*	strdup(char *s).PP.Bchar*	strstr(char *s1, char *s2).PP.Bchar*	cistrstr(char *s1, char *s2).SH DESCRIPTIONThe arguments.I s1, s2and.I spoint to null-terminated strings.The functions.IR strcat ,.IR strncat ,.IR strcpy ,.IR strecpy ,and.I strncpyall alter.IR s1 ..I Strcatand.I strcpydo not check for overflow ofthe array pointed to by.IR s1 ..PP.I Strcatappends a copy of string.I s2to the end of string.IR s1 ..I Strncatappends at most.I nbytes.Each returns a pointer to the null-terminated result..PP.I Strcmpcompares its arguments and returns an integerless than, equal to, or greater than 0,according as.I s1is lexicographically less than, equal to, orgreater than.IR s2 ..I Strncmpmakes the same comparison but examines at most.I nbytes..I Cistrcmpand.I cistrncmpignore ASCII case distinctions when comparing strings.The comparisons are made with unsigned bytes..PP.I Strcpycopies string.I s2to.IR s1 ,stopping after the null byte has been copied..I Strncpycopies exactly.I nbytes,truncating.I s2or addingnull bytes to.I s1if necessary.The result will not be null-terminated if the lengthof.I s2is.I nor more.Each function returns.IR s1 ..PP.I Strecpycopies bytes until a null byte has been copied, but writes no bytes beyond.IR es1 .If any bytes are copied,.I s1is terminated by a null byte, and a pointer to that byte is returned.Otherwise, the original.I s1is returned..PP.I Strlenreturns the number of bytes in.IR s ,not including the terminating null byte..PP.I Strchr.RI ( strrchr )returns a pointer to the first (last)occurrence of byte.I cin string.IR s ,or.L 0if.I cdoes not occur in the string.The null byte terminating a string is considered tobe part of the string..PP.I Strpbrkreturns a pointer to the first occurrence in string.I s1of any byte from string.IR s2 ,.L 0if no byte from.I s2exists in.IR s1 ..PP.I Strspn.RI ( strcspn )returns the length of the initial segment of string.I s1which consists entirely of bytes from (not from) string.IR s2 ..PP.I Strtokconsiders the string.I s1to consist of a sequence of zero or more text tokens separatedby spans of one or more bytes from the separator string.IR s2 .The first call, with pointer.I s1specified, returns a pointer to the first byte of the firsttoken, and will have written anull byte into.I s1immediately following the returned token.The functionkeeps track of its position in the stringbetween separate calls; subsequent calls,signified by.I s1being.LR 0 ,will work through the string.I s1immediately following that token.The separator string.I s2may be different from call to call.When no token remains in.IR s1 ,.L 0is returned..PP.I Strdupreturns a pointer to a distinct copy of the null-terminated string.I sin space obtained from.IR malloc (2)or.L 0if no space can be obtained..PP.I Strstrreturns a pointer to the first occurrence of.I s2as a substring of.IR s1 ,or 0 if there is none.If.I s2is the null string,.I strstrreturns.IR s1 ..I Cistrstroperates analogously, but ignores ASCII case differences when comparing strings..SH SOURCEAll these routines have portable C implementations in.BR /sys/src/libc/port .Many also have machine-dependent assembly languageimplementations in.BR /sys/src/libc/$objtype ..SH SEE ALSO.IR memory (2),.IR rune (2),.IR runestrcat (2),.IR string (2).SH BUGSThese routines know nothing about.SM UTF.Use the routines in.IR rune (2)as appropriate.Note, however, that the definition of.SM UTFguarantees that.I strcmpcompares.SM UTFstrings correctly..PPThe outcome of overlapping moves varies among implementations.