我有一个问题，搜索了大约半天后找不到实际的解决方案。在这个程序中，我必须用客户信息填充一系列结构。我还必须做其他一些事情，但我无法在我的代码中找出这个错误。我知道问题是在扫描客户数量后，输入缓冲区在缓冲区中具有换行符或换行符。许多人建议已经在线使用以下方法：
while((number = getchar()) != 'n' && number != EOF)
/* discard the character */;
这仅适用于输入的名字，然后我在循环中遇到了同样的问题，将新行或换行从客户优先级放在首位。需要有一种方法可以让我取出换行而不必担心它。我不能使用类似fflush();的东西或任何类似的功能。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MIN_CUSTOMERS 2 /* Minimum valid menu choice */
#define MAX_CUSTOMERS 100 /* Maximum valid menu choice */
#define MAX_NAME_LENGTH 21 /* Maximum last name length */
#define END_OF_STRING ' ' /* End of string character */
#define NEW_LINE 'n' /* New line character */
#define QUIT 0 /* Program exit value */
#define DB_ALLOC_ERROR 1 /* Database allocation error */
/**********************************************************************/
/* Program Structures */
/**********************************************************************/
/* A company customer record */
struct customer
{
char customer_name[MAX_NAME_LENGTH]; /* Last name of customer */
float amount_owed; /* Dollar amount customer owes */
int priority; /* Priority number of customer */
};
/**********************************************************************/
/* Function Prototypes */
/**********************************************************************/
void print_heading();
/* Print the heading of the program */
void print_instructions();
/* Print the program instructions */
int get_number_of_customers();
/* Get the number of customers to be recorded */
void get_customers(int quantity,
struct customer *p_customer_records_start);
/* Ask the user for customers and fills them into the database */
void clean_names(int quantity,
struct customer *p_customer_records_start);
/* Clean customer names of everything except letters and spaces */
void sort_customers(int quantity,
struct customer *p_customer_records_start);
/* Sort the array of customers alphabetically */
void print_customers(int quantity,
struct customer *p_customer_records_start);
/* Print the items in the customer database */
/**********************************************************************/
/* Main Function */
/**********************************************************************/
int main()
{
int quantity; /* Amount of customer databases */
struct customer *p_customer_records; /* Pointer to the database */
/* Print the program heading */
printf("nnnnnn");
print_heading();
/* Loop through the number of customer database */
while(print_instructions(),
(quantity = get_number_of_customers()) != QUIT)
{
/* Allocate memory for the experimental scientific data values */
/* and abort if memory is not available */
if((p_customer_records =
(struct customer*)malloc(sizeof(struct customer) * quantity))
== NULL)
{
printf("nERROR NUMBER %d OCCURRED in main()", DB_ALLOC_ERROR);
printf("nCould not allocate memory for experimental data");
printf("nThe program is aborting");
exit(DB_ALLOC_ERROR);
}
/* Get, clean, sort, and print the database of customers */
get_customers(quantity, p_customer_records);
clean_names(quantity, p_customer_records);
sort_customers(quantity, p_customer_records);
print_customers(quantity, p_customer_records);
/* Display end of database processing */
printf("nn******* End of Customer Database Processing *******");
printf("n");
/* Free the database memory that was allocated */
free(p_customer_records);
}
/* Print goodbye and terminate */
printf("nThanks for processing accounts. Have a nice day! :-)");
return 0;
}
这是我得到数量的地方。
/**********************************************************************/
/* Get number of customers */
/**********************************************************************/
int get_number_of_customers()
{
int quantity; /* Quantity of experimental scientific data values */
do
{
printf("nnGet the number of customers for the database");
printf("n- - - - - - - - - - - - - - - - - - - - - - - - - -");
printf("nHow many customers do you have (2 to 100, 0=quit): ");
scanf ("%d", &quantity);
} while (quantity == 1 ||
quantity < QUIT || quantity > MAX_CUSTOMERS);
return quantity;
}
/**********************************************************************/
/* Get customers information */
/**********************************************************************/
void get_customers(int quantity,
struct customer *p_customer_records_start)
{
struct customer *p_customer; /* Points to each customer */
char *p_last_name;
/* Loop through the array of customers and get information */
for(p_customer = p_customer_records_start;
(p_customer-p_customer_records_start) < quantity; p_customer++)
{
/* Get the customer's last name */
printf("n- Customer Information -");
printf("n Enter the customer's last name: ");
p_last_name = p_customer->customer_name;
这就是我的问题出现的地方。
do {
*p_last_name = getchar();
p_last_name++;
} while (*(p_last_name - 1) != NEW_LINE);
*(p_last_name - 1) = END_OF_STRING;
/* Get the amount the customer owes */
printf(" Enter the amount owed: ");
scanf ("%f", &p_customer->amount_owed);
/* Get the customer's priority */
printf(" Enter the customer's priority: ");
scanf("%d", &p_customer->priority);
while(p_customer->priority < 1 || p_customer->priority > 3)
{
printf(" Enter a valid priority (1-3): ");
scanf ("%d", &p_customer->priority);
}
如果我在这里使用 while 循环（前面的解释），优先级永远不会有效，并且无限循环开始。
}
return;
}
这是一个常见问题，解决方案相当简单：每次阅读内容时始终阅读一整行。
切勿在输入缓冲区中保留换行符，以免弄乱以后的读取。不要（就像你现在正在做的那样）把它们留在那里，以后在阅读文本行时尝试跳过它们。始终使用用户键入的整行，包括末尾的换行符。
关于如何做到这一点的通常建议是使用 fgets 或类似的东西来读取行，然后使用 atoi 或 sscanf 或类似的东西处理内容。另一种可能性是，当输入缓冲区中还剩下一个换行符时，始终使用 getchar 立即读取并丢弃换行符。
所以永远不要只这样做：
scanf("%d", &p_customer->priority);
要么这样做：
fgets(line, sizeof line, stdin);
sscanf(line, "%d", &p_customer->priority);
或者，可能，这个：
scanf("%d", &p_customer->priority);
while (getchar() != 'n')
;
使用错误处理，我方便地（对我来说）遗漏了。