c - fflush(stdin) 函数不起作用

Question

我似乎无法弄清楚这段代码有什么问题:

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>


#define MAX 100
#define TRUE 1
#define FALSE 0

char sect_cat;
char customer_name[MAX];
char customer_number[MAX];      /* error handling is easier */

int prev_unit = 0;
int current_unit = 0;
int consumed = 0;
int set = FALSE;

float init_bill;
float tax;
float total_bill;


    void get_userinfo()
    {

            printf("Enter sector category: ");
            scanf("%c", &sect_cat);
        printf("Enter customer name: ");
        fflush(stdin);
        scanf("%sn", &customer_name);

        set = FALSE;
        while (set == FALSE)
        {
            printf("Enter customer number: ");
            fflush(stdin);
            scanf("%s", customer_number);

            int i;
            int error;
            for (i=0, error=0; i<strlen(customer_number); i++)
            {
                if (isdigit(customer_number[i]))
                {
                }
                else
                {
                    error = 1;
                }
            }
            if (error == 0)
            {
                set = TRUE;
            }
            else
                printf("ERROR: Only numbers are allowed\n");
        }

        printf("Enter previous unit: ");
        fflush(stdin);
        scanf("%d", &prev_unit);

        set = FALSE;
        while (set == FALSE)
        {
            printf("Enter current unit: ");
            fflush(stdin);
            scanf("%d", &current_unit);

            if (prev_unit > current_unit)
            {
                printf("ERROR: Current unit must be larger than previous unit\n");
            }
            else
                set = TRUE;
        }
        consumed = current_unit - prev_unit;
    }



int main()
{


/* Introduce program to users */

        printf("\nThis program computes your electric bill based on these sector categories\n\n");

    printf("\tResidential(R)\n");
    printf("\tIndustrial(I)\n");
    printf("\tCommercial(C)\n\n");

    printf("Press any key to continue...");
    fflush(stdin);
    getchar();  

＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃＃ 编辑

应用 templatetypedef 的解决方案，程序现在等待用户输入 customer_name。然而，输入带有空格的字符串会导致错误，并且程序假定在下一个提示中输入空格后面的单词。

Enter sector category: r
Enter customer name: George of the Jungle
Enter customer number: ERROR: Only numbers are allowed
Enter customer number: ERROR: Only numbers are allowed
Enter customer number:

Answer 1

fflush 函数不会将数据从输入流中刷新；相反，它用于将输出流中缓冲的数据推送到目的地。这已记录在案here 。如this earlier SO question中所示，尝试使用 fflush(stdin) 会导致未定义的行为，因此最好避免它。

如果您想从用户完成输入字符时输入的返回字符中删除换行符，请考虑以下内容:

scanf("%c%*c", &sect_cat);

这将吃掉换行符，而不是将其留在 stdin 中。

希望这有帮助!