爲什麼我的閱讀類型爲空？

Question

嗯，我編碼這一些功課，我知道它可以更好地修改，並可以使用一些更多的意見，但這一個錯誤正在殺死我......想知道如果它只是我或某事，但你能告訴我，如果錯誤發生在你身上。

錯誤：閱讀類型沒有任何數據。

（你可以使用這些投入，現在因爲我沒有錯誤檢查程序） 測試變量：

 
2345 
AA 
20 
30 
40 
50 
60 
10 
R(supposed to be entered) but program skip 

它是假設採取輸入rea_type但它並繼續跳到其他線路。

下面是代碼：

const float deposit = 1500.00; 
const unsigned multiplier =1; 
const float rate_One = 6.350; 
const float rate_Two = 14.520; 
unsigned bill_Cycle = 0, 
     no_Days = 0; 
float bi_Exch_Rate = 0, 
     ba_Exch_Rate = 0; 
float cur_Read=0, 
     prev_Read=0, 
     cur_Usage=0, 
     cur_Peri_Charg=0; 
char c_Digit[20], 
    premis_numb[20]; 
char rea_type; 
/**Information to be collected from the user**/ 
     system("cls"); 
     printf("\nPlease enter the customer digits: "); 
     scanf("%s",&c_Digit); 
     printf("\nPlease enter Premise Number:"); 
     scanf("%s",&premis_numb); 
     printf("\nPlease enter the Billing Cycle: "); 
     scanf("%d",&bill_Cycle); 
     printf("\nPlease enter the No. of Days: "); 
     scanf("%d",&no_Days); 
     printf("\nPlease enter the Billing Exchange Rate: "); 
     scanf("%f",&bi_Exch_Rate); 
     printf("\nPlease enter the Base Exchange Rate: "); 
     scanf("%f",&ba_Exch_Rate); 
     printf("\nPlease enter the Current Reading: "); 
     scanf("%f",&cur_Read); 
     printf("\nPlease enter the Previous Reading: "); 
     scanf("%f",&prev_Read); 
     printf("What is the Reading Type: "); 
     scanf("%c",&rea_type); 
     cur_Usage = cur_Read-prev_Read; 
     if (cur_Usage<100) 
     { 
      cur_Peri_Charg = cur_Usage*rate_One; 
     } 
     else 
     { 
      cur_Peri_Charg = (((cur_Usage-100) * rate_One)+(cur_Usage*rate_Two)); 
     } 
     strcat(premis_numb,c_Digit);/**Joins the Premis Number and the Customer digits together**/ 
/**Information to be displayed showing user all input and calculations.**/ 
    system("cls"); 
printf("\tStored constants for calculation of customer bill\n"); 
printf("  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n"); 
printf("  Customer Number:%s",premis_numb); 
printf("   Current Usage:%.2f \n",cur_Usage); 
printf("\n"); 
printf("  Billing Cycle:%d\t\t  No of Days:%d\n",bill_Cycle,no_Days); 
printf("\n"); 
printf("  Billing Exchange Rate:%.2f  Base Exchange Rate:%.2f\n",bi_Exch_Rate,ba_Exch_Rate); 
printf("\n"); 
printf("  Deposit:%.2f\t\t  Multiplier:%d\n",deposit,multiplier); 
printf("\n"); 
printf("  Rate 1:%.3f\t\t  Rate 2:%.3f\n",rate_One,rate_Two); 
printf("\n"); 
printf("  Current Reading:%.2f\t  Previous Reading:%.2f\n",cur_Read,prev_Read); 
printf("\n"); 
printf("  Current Usage Reading:%.2f Reading Type:%c\n",cur_Peri_Charg,rea_type); 
printf("  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n"); 

Answer 1

考慮使用字符串rea_type因爲這將是更強大的壞輸入比單個字符，即改變：

char rea_type; 

到：

char rea_type[20]; 

和：

scanf("%c",&rea_type); 

到：

scanf("%s", rea_type); 

---

另外請注意，您應同時更改：

scanf("%s",&c_Digit); 

和：

scanf("%s",&premis_numb); 

到：

scanf("%s", c_Digit); 

和：

scanf("%s", premis_numb); 

你並不需要採取一個字符串的地址，因爲它已經是有效的指針。在這種情況下並不重要，但當字符串確實是指針（而不是數組）時，這是一個很好的習慣。

Answer 2

您不需要傳遞char []的引用。 premin_num & c_Digit是char []的起始地址。做這樣的

scanf("%s",premis_numb); 
scanf("%s",c_Digit); 

一個可能的原因，你的編譯器在rea_type scanf函數跳過輸入是因爲有用戶輸入一個換行符，so if there's a stray newline in the input stream (from a previous entry, for example) the scanf call will consume it immediately & skip taking input.

解決方案：

之前提供空間%c

scanf(" %s",&rea_type); 

Answer 3

它不會跳過讀取字符，它會在最後一個scanf後面的輸入緩衝區中讀取換行符。

這是簡單的修復，告訴scanf跳過前導空白：

scanf(" %c", &rea_type); 

通知的格式代碼前的空格。