"C also provides several byte-limited versions of the copy and concatenation functions:\n\nchar *strncpy(char *dest, const char *src, size_t n);\n\nchar *strncat(char *dest, const char *src, size_t n);\n\nThey work similarly in that they copy/concatenate the source, src string into the destination, dest string. However, there is a third parameter, n which specifies at most how many bytes to copy/concatenate. The parameter, n allows you to limit the number of characters that the operation uses. If either of these functions encounters the null-terminating character before n bytes have been copied/concatenated, they stop and copy the null-terminating character for us. However, these functions do not always handle the null-terminating character for us. If the null-terminating character appears in the first n bytes, it will be copied for us, but if it is not, we need to be sure to handle it ourselves.\n\nFor example,\n\n1 char email[] = \"twaits@cse.unl.edu\";\n\n2 char *login = (char *) malloc(7 * sizeof(char));\n\n3\n\n4 //only copy the first 6 characters:\n\n5 strncpy(login, email, 6);\n\n6 //at this point, login contains \"twaits\" but is\n\n7 //not null-terminated, so we manually terminate it\n\n8 login[6] = '\\0';\n\nThe byte-limited versions of the copy function can be used to compute a substring of another string. The parameter n can be used to limit the length of the string, but how might we specify where the substring should start? For example, in the string \"Thomas Alan Waits\" we may want to get the substring representing his middle name, \"Alan\". The length is 4 and we can specify that the copying should start by using an index. In this case, we want the copying to start at index 7, the 8th character. If the string is stored in an array named name, this would be name[7]. However, indexing an array like this results in a single character and strncpy() expects a string (a character pointer). Fortunately, we know how to do this:"