string.h – cstring

strcpy()	char *strcpy(char *str1, const char *str2);
strncpy()	char *strncpy(char *str1, const char *str2, size_t n);
strcat()	char *strcat(char *str1, const char *str2);
strncat()	char *strcat(char *str1, const char *str2, size_t n);

memcpy()	void *memcpy(void *str1, const void *str2, size_t n);
memmove()	void *memmove(void *str1, const void *str2, size_t n);
memset()	void *memset( void *str, int c, size_t n);
strchr	char *strchr(const char *str, int c);
strrchr	char *strrchr(const char *str, int c);
strstr()	char *strstr(const char *str1, const char *str2);

strlen()	size_t strlen(const char *str);
strcmp()	int strcmp(const char *str1, const char *str2);
strncmp()	int strncmp(const char *str1, const char *str2, size_t n);
memcmp()	int memcmp(const void *str1, const void *str2, size_t n);

strcoll Compare two strings using locale (function)
strxfrm Transform string using locale (function)
memchr Locate character in block of memory (function)
strcspn Get span until character in string (function)
strpbrk Locate character in string (function)
strspn Get span of character set in string (function)
strtok Split string into tokens (function)
strerror Get pointer to error message string (function)
NULL Null pointer (macro)
size_t Unsigned integral type (type)