enum { BUFFER_SIZE = 10 };
char str1[BUFFER_SIZE];
char str2[]="abcdefghijklmn";

strncpy(str1,str2, BUFFER_SIZE); /* limit number of characters to be copied */
// We need to set the limit to BUFFER_SIZE, so that all characters in the buffer
// are set to '\0'. If the source buffer is longer than BUFFER_SIZE, all the '\0'
// characters will be overwritten and the copy will be truncated.

if (str1[BUFFER_SIZE-1] != '\0') {
    /* buffer was truncated, handle error? */
}