我的案例陈述方法在c中两次打印一个句子

Question

I am trying to work with a switch-statement. But it doenst really work for me, because if I run it, it prints the sentence ''task 1 = A, task 2 = B, task = C\\n'' twice after I choose A, B or C. Why is this/ What do I do wrong?

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

main()
{
  int b;
     while (b)
     {
     char a;
  printf("task 1 = A, task 2 = B, task = C\n");
  scanf("%c", &a);


  switch ( a )
  {

     case 'A':
         printf("task 1\n");

     break;

     case 'B':
          printf("task 2\n");

     break;


     case 'C':
           printf("task 3\n");
     break;
}
}
}

Answer 1

On next iteration scanf read the \\n character left behind by previous scanf in input buffer. A space before %c is able to consume any number of white-spaces.
Try this

scanf(" %c", &a);
       ^ Place a space before `%c  

Another thing is that you have not initialized b . Your program invokes undefined behavior.