I just take the written test of Wuhan bonfire back, one of the questions to implement the strcpy () function, if not guess, should be learned from Lin Rui's "high quality C_C programming", write:
Char * STRCPY (Char * DESC, CHAR * SRC)
{
Char * p;
IF (src == NULL) exit (0);
IF (DESC == SRC) Return DESC;
P = DESC;
While (* src == '/ 0')
* DESC = * SRC ;
Return P;
}
Lin Rui's answer:
Char * STRDEST, Const Char * strsrc);
{
Assert (strDest! = null) && (strsrc! = null); // 2 points
Char * address = strDest; // 2 points
While (* strDest = * strsrc )! = '/ 0') // 2 points
NULL;
Return Address; // 2 points
}
Just yesterday
See a post on 9CBS discussion strcpy ();
A little explanation for the relevant content:
Void test1 ()
{
INT I;
Char string [10];
CHAR * STR1 = "0123456789";
STRCPY (String, Str1);
// Character offshore?
/ * Error: STRCPY (DESC, SRC), when SRC <= DESC, such as Char * STR1 = "012345678", the length is 10, then string gets a reasonable value, and string [9] = '/ 0'; when SRC When DESC, such as char * str1 = "0123456789", the length is 11, then string gets the value of 0-9, String [9] = '9', although it can be run, but String [9] is not String The characters are maliciously modified to '/ 0', which is not what we want, or may cause serious consequences. * / Printf ("% s / n", string);
For (i = 0; i <11; i
) // deliberately loop 11 times, check the last byte that is unintentionally modified; {
Printf ("% C / T% D / N", String [i], string [i]);
}
Printf ("/ n");
}
Void test2 ()
{
INT I;
Char String [100], STR1 [10];
For (i = 0; i <10; i )
{
STR1 [I] = 'a';
}
STRCPY (String, Str1);
/ * STRCPY (DESC, SRC) treats SRC as a string type, copying the '/ 0' ending, as the end of the SCR, is paid to DESC; so although the program can run, but potential problems: STR1 All 10 elements are initialized to 'a', but subsequent characters are unpredictable until "accidentally" hit '/ 0', only stop identifying Str1; if string is a large group of 100 elements, it will be found "Random Elements" behind STR1 are also copied to String until "accident", the quotation number, in fact, '/ 0' is quite a lot in the unknown memory. Of course, if DESC is String [10], it will turn off the STR1, which is the correct operation of the surface; * / printf ("% s / n", string); for (i = 0 i <100; i )
{
Printf ("% C / T% D / T% C / N", String [i], string [i], str1 [i]);
// Contrast;
}
Printf ("/ n");
}
