Could you please help me implement these functions in C language without using stdio.h library(don't use like strcmp() strlen())

int mystrncmp(const char *s11 const char *s2. int n The function compares up to "n" characters of the string pointed to by "s" to the string pointed to by "s2 . The function returns an integer (1), (0), or (-1), accordingly as the string to by "s1" is greater than, equal to, or less than the string pointed to by "s2" in the irst "n" bytes. char *mystrncpy(char *dest.const char *src int n) The function copies no more than "n" characters from the null-terminated string pointed to by "src" to the memory pointed to by "dest". The destination shall be padded with null characters. The function returns the pointer "dest"; the function has no failure mode and no error return. int mystrrchr(const char s, int c) The function locates the last occurrence of "c" (converted to a char) in the string pointed to by "s". The terminating null character is considered to be part of the string. The function returns the position of "c" found, or (-1) if the character was not found