Question

我不明白为什么不执行要求用户重量输入的最后一行。这可能是记忆问题吗？或者我错误地写了结构？或者我是否错误地写了对scanf（）的调用？或者以上所有？

#include <stdio.h>

struct date{
  int month;
  int day;
  int year;
};

struct healthProfile{
  char firstName[20];
  char lastName[20];
  struct date birthday;
  float height; //inches
  float weight; //pounds
};



int main(void)
{
  struct healthProfile patient1;

  printf("%s\t", "Please enter the patient's first name:");
  scanf("%s", patient1.firstName);


  printf("%s\t", "Please enter the patient's last name:");
  scanf("%s", patient1.lastName);

  printf("%s\t", "Please enter the date of birth(mm/dd/yyyy)");
  scanf("%2i/%2i/%4i", &patient1.birthday.month, &patient1.birthday.day, &patient1.birthday.year);

  printf("%s\t", "Please enter the patient's height in inches");
  scanf("%.2f", &patient1.height);

  printf("%s\t", "Please enter the patient's weight in pounds");
  scanf("%.2f", &patient1.weight);



  return 0;
}

Answer 1

与printf不同，scanf的格式说明符不具有精确性。编译器应该警告你：

x1.c: In function ‘main’:
x1.c:34:3: warning: unknown conversion type character ‘.’ in format [-Wformat=]
   scanf("%.2f", &patient1.height);
   ^
x1.c:34:3: warning: too many arguments for format [-Wformat-extra-args]
x1.c:37:3: warning: unknown conversion type character ‘.’ in format [-Wformat=]
   scanf("%.2f", &patient1.weight);
   ^
x1.c:37:3: warning: too many arguments for format [-Wformat-extra-args]

删除精度，您将能够正确阅读：

printf("%s\t", "Please enter the patient's height in inches");
scanf("%f", &patient1.height);

printf("%s\t", "Please enter the patient's weight in pounds");
scanf("%f", &patient1.weight);

Answer 2

当您从控制台接收输入时，它是行缓冲的，但％f格式说明符仅提取数字数据，将换行符（至少）保留在缓冲区中。下一个输入将丢弃前导空格（前一个调用的换行符），但是对于您需要的最后一个输入或丢弃它。一种方式：

  int c ;
  while ((c = getchar()) != '\n' && c != EOF) { }
  scanf("%f", &patient1.weight);

然而，在任何不使用换行符的输入之后执行此操作是个好主意，并且在这种情况下更简单地将输入包装在函数中说getfloat()以减少重复。

内存问题阻止输入结构？

2 个答案: