奇怪的事情用一個簡單的程序，可能scanf的問題

Question

我有一個簡單的功課......做一個C程序，需要3個值3倍

1. 食品（焦炭）的ID
2. CAL值食品（浮點）
3. 量食品（浮點）的

下面是代碼和輸出程序給出我：

#include <stdio.h> 
#define NUM_OF_FOOD 3 

int main() 
{ 
    float food_cal[NUM_OF_FOOD]; 
    float food_amount[NUM_OF_FOOD]; 
    char food_id[NUM_OF_FOOD]; 
    int i; 
    float total_cal=0; 
    int most_fat_food_id=0; 
    printf("enter the following data: food ID, Cal value and Amount eaten \nexample A 10 3\n"); 
    for (i=0;i<NUM_OF_FOOD;i++) 
    { 
     printf("\nEnter product #%d:",i); 
     int inputLength = scanf("%c %f %f",&food_id[i],&food_cal[i],&food_amount[i]); 
     if (inputLength < 3) { 
      printf("input error, input length was %d excpexted 3", inputLength); 
      break; 
     } 
     if (!((food_id[i]>96 && food_id[i]<123) || (food_id[i]>64 && food_id[i]<91))) { 
      printf("ID input error"); 
      break; 
     } 
     if (food_cal[i] < 0) { 
      printf("Food Cal input error"); 
      break; 
     } 
     if (food_amount[i] < 0) { 
      printf("Food Amount input error"); 
      break; 
     } 
     printf("\n%c %5.2f %5.2f",food_id[i],food_cal[i],food_amount[i]); 
    } 
    for (i=0;i<NUM_OF_FOOD;i++) 
     total_cal+=food_cal[i]*food_amount[i]; 

    printf ("\nTotal amount of calories is %5.2f\n",total_cal); 
    for (i=1;i<NUM_OF_FOOD;i++) 
     most_fat_food_id = (food_cal[most_fat_food_id]<food_cal[i]) ? i : most_fat_food_id; 

    printf ("\nThe most fattening product is: %c with %5.2f calories",food_id[most_fat_food_id],food_cal[most_fat_food_id]); 

    return 0; 
} 

/* 
enter the following data: food ID, Cal value and Amount eaten 
example A 10 3 

Enter product #0:A 1000 2 

A 1000.00 2.00 
Enter product #1:B 500 3 
input error, input length was 1 excpexted 3 
Total amount of calories is 2000.00 

The most fattening product is: A with 1000.00 calories 
*/ 

它只是跳過第三

不知道爲什麼......兩個人看了看號碼的輸入，看起來不錯，但還是有一個錯誤。

Answer 1

輸入：甲1000 2 [ENTER]乙500 3 [ENTER] ...

第一scanf("%c %f %f")讀取 'A'，1000，和2以及在[ENTER]

第二停止scanf("%c %f %f")讀取[ENTER]和扼流圈B與「％f」轉換。

您可以嘗試在讀取char之前使用scanf(" %c %f %f")強制跳過可選空白。

Answer 2

你不消耗 '\ n'

快速/骯髒的方法是添加一個變量：您scanf()後

char readNewLine; 

，再添：

scanf("%c", &readNewLine); 

這很醜陋，但它已經足夠了 - 在使用C一段時間後，更好的方法將變得可用。

Answer 3

線33加後：

char nl = 0; 
scanf("%c", &nl); 

，這將消耗多數民衆贊成擰事情最終換行符。

上述建議後，這是輸出：

./test 
enter the following data: food ID, Cal value and Amount eaten 
example A 10 3 

Enter product #0:a 10 2 

a 10.00 2.00 
Enter product #1:b 3 29 

b 3.00 29.00 
Enter product #2:c 32 4 

c 32.00 4.00 
Total amount of calories is 235.00 

The most fattening product is: c with 32.00 calories