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這是我的第一篇文章。我搜索了一下，但找不到任何特定於我的問題，有助於解決它。當我試圖解引用指針或在函數中應用指針數學時，事情並沒有做到他們應該做的。爲什麼我的程序（sort_them函數）沒有排序？
例如：*（ptr + a）應該在技術上推進一個指向我設定的值的指針。相反，我只是得到一個錯誤，表示「請求成員'名稱'的東西不是結構或聯盟」。這是沒有道理的，因爲我已經聲明並將我的結構指針傳遞給函數。如果我使用：「start_ptr-> name.last + a」風格，它會編譯但不排序任何內容。我知道這第二個版本也是不正確的，當涉及到指針數學。
所以基本上，看起來錯在編譯，看起來正確的不是，實際上也沒有排序任何東西。
下面是代碼
#include <stdio.h>
#include <string.h>
#include <ctype.h>
/* Structure definition */
/* -------------------- */
struct split
{
char last[10];
char first[10];
};
struct info
{
struct split name;
char address[20];
char city[15];
char state[3];
long zip;
int age;
char gender;
}; /* end struct info */
void sort_them(struct info *, char); // sort prototype
int main(void)
{
/* Declare variables */
/* ----------------- */
struct info people[] =
{
{"Asimov", "Isaac", "15 Main St", "Worcestor", "MA", 01555, 23, 'M'},
{"Smith", "Jane", "17 Make Peace", "Wallham", "ND", 10102, 28, 'F'},
{"De Rippa", "Jack", "18 Able Way ", "Boston", "MA", 50503, 74, 'M'},
{"Cobb", "Jim", "55 Elm St", "Ware", "MO", 61555, 65, 'M'},
{"Kapone", "Al", "15 Morin Ave", "Idunno", "MN", 31333, 34, 'M'},
{"Seigel", "Myron", "44 Wing Blvd West", "Sandwich", "WA", 02537, 21, 'M'},
{"Thymes", "Mary", "88 Same Place", "Washington", "DC", 90555, 44, 'F'}
};
int bad_sort;
int num_people = sizeof(people)/sizeof(people[0]); //this will be the count of how many people there are!
char sort_order;
char big_name[22];
struct info *start_ptr = &people[0];
struct info *nums_ptr, *nums_end_ptr = &people[6];
char *big_ptr = &big_name[0];
printf ("\nWelcome to the People Structure Data Report Program\n");
do
{
bad_sort = 1;
printf ("\nEnter the sort order for the report: ");
printf ("\n(N=Name, A=Age, S=State, Z=Zip code ' '=no sort)\n ");
/* blank or return is allowed for no sorting of the data */
sort_order = getchar();
if(sort_order == '\n' || sort_order == ' ') break;
sort_order = toupper(sort_order);
if ((sort_order == 'N') || (sort_order == 'A') ||
(sort_order == 'S') || (sort_order == 'Z'))
bad_sort = 0;
else
printf("\nIncorrect Sort order selected, please re-enter: ");
} while (bad_sort == 1);
switch (sort_order)
{
case 'N':
printf("Sort by Name %i People.\n", num_people);
break;
case 'A':
printf("Sort by Age %i People.\n", num_people);
break;
case 'S':
printf("Sort by State %i People.\n", num_people);
break;
case 'Z':
printf("Sort by Zip %i People.\n", num_people);
break;
default:
printf("No Sort selected %i People.\n", num_people);
break;
} /* end cases */
if(sort_order != ' ')
sort_them (start_ptr, sort_order);
/* Print Report */
/* ------------ */
printf("\n\n The People Report\n\n");
printf ("\n\n%-20s%-20s %-15s %-5s %-6s %-3s %-6s",
"Name", "Address","City","State","Zip","Age","Gender");
printf ("%-20s%-20s %-15s %-5s %-6s %-3s %-6s\n",
"----", "------","----","-----","---","---","------");
for (nums_ptr = start_ptr; nums_ptr <= nums_end_ptr; nums_ptr++, start_ptr++)
{
strcpy(big_ptr, start_ptr->name.last);
strcat(big_ptr, ", ");
strcat(big_ptr,start_ptr->name.first);
printf ("%-20s%-20s %-15s %-4s%.5ld %-3i %c\n",
big_ptr,start_ptr->address,start_ptr->city,start_ptr->state,start_ptr->zip,
start_ptr->age,start_ptr->gender);
} /* end for loop */
printf("\n\n");
return 0;
} /* end main */
void sort_them(struct info *start_ptr, char sort_by)
{
int a,b;
struct info temp;
for(a = 0; a < 6; a++)
for(b = a + 1; b < 7; b++)
{
if( (sort_by == 'N' && strcmp(start_ptr->name.last + a, start_ptr->name.last + b) > 0)
|| (sort_by == 'A' && start_ptr->age + a > start_ptr->age + b)
|| (sort_by == 'S' && strcmp(start_ptr->state + a, start_ptr->state + b) > 0)
|| (sort_by == 'Z' && (start_ptr->zip + a) > (start_ptr->zip + b))
)
{
temp = *(start_ptr + a);
*(start_ptr + a) = *(start_ptr + b);
*(start_ptr + b) = temp;
} /* end if */
} /* end inner for loop */
};
/* end of sort them