glibc实现

string.h

strcpy 复制一个字符串给另一个
strncpy 从一个字符串复制一定数量的字符到另一个
strcat 连接两个字符串
strncat 连接两个字符串的一定数量字符
strxfrm transform a string so that strcmp would produce the same result as strcoll

strlen 返回给定字符串的长度
strcmp 比较两个字符串
strncmp 比较两个字符串的一定数量字符
strcoll compares two strings in accordance to the current locale
strchr 查找字符的首次出现
strrchr 查找字符的最后一次出现
strspn returns the length of the maximum initial segment that consists of only the characters found in another byte string
strcspn returns the length of the maximum initial segment that consists of only the characters not found in another byte string
strpbrk finds the first location of any character in one string, in another string
strstr 查找子串字符的首次出现
strtok 查找字节字符串中的下一个记号