c - 对用户输入进行错误处理，直到输入正确

Question

这段代码首先应该告诉用户输入要检查的三角形的数量。如果用户没有输入整数，则程序会告诉用户再次输入整数，直到输入为止。

然后用户必须输入三元组的 float 。继续在这里工作得很好。但对于第二个三元组，如果用户没有输入整数(例如输入 2x)，它将返回到 while 循环的顶部，即请输入三元组的第一个数字。如何编辑我的代码，使其不会转到 while 循环的顶部，而是告诉用户再次输入三元组的第二个数字？

#include <stdio.h>
#include <stdlib.h>
#define request "Please enter the number of triangles to check: "
#define triplet1 "Please enter the first number of the triplet: "
#define triplet2 "Please enter the second number of the triplet: "
#define Error "[ERR] Invalid number of triangles.\n "
#define Error2 "[ERR] Invalid number for the triplet.\n"
#define UCHAR_MAX 20

int main ()
{

  int triangles = 0;
  char *end;

  for (;;)
    {
      printf ("%s", request);
      char buffer[30];
      fgets (buffer, sizeof (buffer), stdin);
      triangles = strtol (buffer, &end, 10);
      if (*end != '\n' || triangles < 1 || triangles > UCHAR_MAX)
    {
      printf ("%s", Error);

      continue;
    }
      break;
    }

  float triplet[3] = { 0.0, 0.0, 0.0 };
  int i = 0;
  while (i < triangles)
    {
      float tmp = 0.0;
      printf ("%s\n", triplet1);
      char buffer[30];
      fgets (buffer, sizeof (buffer), stdin);
      tmp = strtol (buffer, &end, 10);
      if (*end != '\n' || tmp < 1)
    {
      printf ("%s", Error2);
      continue;

    }
      triplet[0] = tmp;
     tmp = 0.0;
      printf ("%s\n", triplet2);

      fgets (buffer, sizeof (buffer), stdin);
      tmp = strtol (buffer, &end, 10);
      if (*end != '\n' || tmp < 1)
    {
      printf ("%s", Error2);
      continue;              // goes back to the top of the while loop 

    }

      triplet[1] = tmp;


      i++;

    }

return 0;
}

Answer 1

这是 continue 语句的预期行为。您需要为此实现内部循环。

如果您想在用户输入正确的值之前接受输入，请尝试以下操作:我没有 C 编译器，所以无法测试，但希望它应该可以工作。如果您发现任何问题，请告诉我。

while (i < triangles)
{
  float tmp = 0.0;
  char buffer[30];
  whiel(true){
    printf ("%s\n", triplet1);
  fgets (buffer, sizeof (buffer), stdin);
  tmp = strtol (buffer, &end, 10);
  if (*end != '\n' || tmp < 1)
    {
      printf ("%s", Error2);
      continue;
    }
    triplet[0] = tmp;
    break;
  }

 tmp = 0.0;
  while(true){
    printf ("%s\n", triplet2);
  fgets (buffer, sizeof (buffer), stdin);
  tmp = strtol (buffer, &end, 10);
  if (*end != '\n' || tmp < 1)
    {
         printf ("%s", Error2);
        continue;
    }
      triplet[1] = tmp;
      i++;
       break;
    }
  }