fivePointFive() {
/* s is an array while p is a point, the case below show the difference.
* The same thing for them is both them can visit value by adding steps.*/
char s[] = "i love you"; /* s can not be refered to another address, but string content can be modified.*/
// s = "iii"; //this will cause a compile error, for s is not a pointer.
*(s + 1) = 'i'; // this is well, because for an array, the value can be modified.
printf("%s %c\n", s, *s);
char *p = "i love you"; /* p can be refered to another address, but string content can not be modified. */
p = "you love me"; // this is well, because p is a point, not a name of array.
// *(p + 1) = 'u'; // this will cause a runtime error, for p can not modify the value.
printf("%s %c\n", p, *p);
// char *p = "you love me"; p will be pointed to an anonymous string, so it can't modify the value.
// s = p; s++; //this will cause a compile error, for s is not a pointer.
p = s; /* p now refered to an array and can be used just like s to modify the string content.*/
*(p + 1) = ' ';
printf("%s\n", p);
// char *ss = "123"; This will cause a runtime error, for ss should be an array which its value is allowed to be modified.
char ss[10] = "123";
char *tt = "456"; // Here, use pointer is ok, for we just visit the value, no modification.
printf("%s compared with %s: %d\n", ss, tt, strcmp(ss, tt));
strcpy(ss, tt);
strcpy1(ss, tt);
strcpy2(ss, tt);
strcpy3(ss, tt);
strcpy4(ss, tt);
printf("copy tt to ss get %s\n", ss);
printf("%s compared with %s: %d\n", ss, tt, strcmp2(ss, tt));
}
int main(void)
{
char s[100];
char *t = "Test strcpy;";
strcpy1(s,t);
printf("%s\n", t);
strcpy2(s,t);
printf("%s\n", t);
strcpy3(s,t);
printf("%s\n", t);
strcpy4(s,t);
printf("%s\n", t);
strcpy1(s+strlen1(s),t);
printf("%s\n", s);
printf("%d\n", strcmp1(s,t));
printf("%d\n", strcmp2(s,t));
return 0;
}
