如果你想要相反的str2
早在main()
,您需要将足够大小的缓冲区传递给reverse_const
保存反转的字符串,否则您将需要为其动态分配存储空间reverse_const
(局部可变长度数组不行):
#include <stdlib.h>
...
void reverse_const (const char **str_const)
{
int c_size = strlen (*str_const);
char *str = calloc (c_size + 1, sizeof *str);
strcpy (str, *str_const);
char *c_begin = str, *c_end = str + (c_size - 1);
int i;
for (i = 0; i < c_size / 2; i++) {
*c_begin ^= *c_end;
*c_end ^= *c_begin;
*c_begin ^= *c_end;
c_begin++;
c_end--;
}
*str_const = str;
printf ("%s\n", *str_const);
}
int main (void) {
char str1[] = "Indiana";
char *str2 = "Kentucky";
printf ("TESTS:\nString 1 pre-reversal: %s\n", str1);
reverse (str1);
printf ("String 1 post-reversal: %s\n", str1);
printf ("Constant string 2 pre-reversal: %s\n", str2);
reverse_const ((const char **)&str2);
printf ("Constant string 2 post-reversal: %s\n", str2);
free (str2);
return 0;
}
Output
$ ./bin/revconststr
TESTS:
String 1 pre-reversal: Indiana
String 1 post-reversal: anaidnI
Constant string 2 pre-reversal: Kentucky
ykcutneK
Constant string 2 post-reversal: ykcutneK
返回指针
您还有一个附加选项可以将指针返回到str
分配给str2
in main()
。这更符合您通常期望看到的情况。如果您有任何疑问,请告诉我:
char *reverse_const2 (const char **str_const)
{
int c_size = strlen (*str_const);
char *str = calloc (c_size + 1, sizeof *str);
strcpy (str, *str_const);
char *c_begin = str, *c_end = str + (c_size - 1);
int i;
for (i = 0; i < c_size / 2; i++) {
*c_begin ^= *c_end;
*c_end ^= *c_begin;
*c_begin ^= *c_end;
c_begin++;
c_end--;
}
//*str_const = str;
printf ("%s\n", *str_const);
return str;
}
int main (void)
{
char str1[] = "Indiana";
char *str2 = "Kentucky";
printf ("TESTS:\nString 1 pre-reversal: %s\n", str1);
reverse (str1);
printf ("String 1 post-reversal: %s\n", str1);
printf ("Constant string 2 pre-reversal: %s\n", str2);
str2 = reverse_const2 ((const char **)&str2);
printf ("Constant string 2 post-reversal: %s\n", str2);
free (str2);
return 0;
}