#include <strings.h> int strcasecmp(const char *s1, const char *s2); int strncasecmp(const char *s1, const char *s2, size_t n); char *index(const char *s, int c); char *rindex(const char *s, int c); #include <string.h> char *strcat(char *dest, const char *src); char *strchr(const char *s, int c); int strcmp(const char *s1, const char *s2); int strcoll(const char *s1, const char *s2); char *strcpy(char *dest, const char *src); size_t strcspn(const char *s, const char *reject); char *strdup(const char *s); char *strfry(char *string); size_t strlen(const char *s); char *strncat(char *dest, const char *src, size_t n); int strncmp(const char *s1, const char *s2, size_t n); char *strncpy(char *dest, const char *src, size_t n); char *strpbrk(const char *s, const char *accept); char *strrchr(const char *s, int c); char *strsep(char **stringp, const char *delim); size_t strspn(const char *s, const char *accept); char *strstr(const char *haystack, const char *needle); char *strtok(char *s, const char *delim); size_t strxfrm(char *dest, const char *src, size_t n);