what is a substring in c code example

Example 1: c substring

//where we want the word "test" and we know its position in the string
char *buff = "this is a test string";
printf("%.*s", 4, buff + 10);

Example 2: c substring

char subbuff[5];
memcpy( subbuff, &buff[10], 4 );
subbuff[4] = '\0';