I didnt even ask to print double quotes. But it keeps printing after I put an input starting with D. When i put 'C', the output is normal. Example:

input > D

2

9

egdqncekq

B4 i put "egdqncekq", the program prints a double quotes for some reason.

#include <stdio.h>
int main() {
  char cd, m;
  int size, i, disp, m1;
 
  cd=getchar();
  scanf("%d", &disp);
  scanf("%d", &size);
 
  switch(cd)
  {
  case 'C':
  for(i=0; i<=size; i  )
  {
    m=getchar();
    m1=m disp;
    if(m1>122)
    {
      m1=m1-26;
    }
    printf("%c", m1);
  }
  break;

  case 'D':
    for(i=0; i<=size; i  )
    {
      m=getchar();
      m1=m-disp;
      if(m1<97)
      {
        m1=m1 26;
      }
      printf("%c", m1);
    } 
    break;
  }
  printf("\n");
  return 0;
}

CodePudding user response：

After the second scanf there's a newline character (ASCII 10) left in the input buffer. That newline gets picked up by the getchar function in each of the loops.

In the "C" case, 2 is added to this value which results in 12. This is the ASCII form feed character which prints as an extra newline.

In the "D" case, 2 is subtracted from this value resulting in 8. This value is less than 97 so 26 is added resulting in 34, which is the ASCII code for the " character which then gets printed.

Before entering the switch statement, you should call getchar in a loop until you see a newline. That will flush out the input buffer.