C language learning log 12.25

String function

include<string.h>

        (1)strlen: strlen( String name )——— Represents the length of the string , Not including the ending "\0".

        (2)strcmp: int strcmp(const char*s1,const char *s2)—— To compare these two strings , return :(1).s1==s2:0;(2).s1>s2:1;(3).s1<s2:-1

        (3)strcpy: char*strcpy(char *restrict dst, const char*restrict src)——— Used to handle src Copy characters of to dst,restrict indicate src and dst No overlap , In the end, it's back dst

        (4)strcat:char *strcat(char*restrict s1,const char *restrict s2)—— hold s2 copy to s1 Behind , Take a long string , return s1,s1 There must be enough space

        among （2）(3) (4) Add... In the middle n, such as strncpy(char *restrict dst, const char*restrict src,size_t n);—— To copy n Advance in dst.

        (5)strchr:char * strchr(const char*s,c);—— Look for... From the left , Used to find... In a string c character .strrchr： It's from the right .