如何在C语言中一一输入字符串

Question

I have to take inputs like below, and print the same (only the sentences):

2

I can't believe this is a sentence.

aarghhh... i don't see this getting printed.

Digit 2 shows the number of lines to be followed (2 lines after this here). I used all the options scanf and fgets with various regex used.

int main() {
  int t;
  char str[200];
  scanf ("%d", &t);      
  while (t > 0){
  /* 
  Tried below three, but not getting appropriate outputs
  The output from the printf(), should have been:

  I can't believe this is a sentence.
  aarghhh... i don't see this getting printed.
  */
    scanf ("%[^\n]", str);
    //scanf("%200[0-9a-zA-Z ]s", str);
    //fgets(str, 200, stdin);
    printf ("%s\n", str);
    t--;
  }
}

I am sorry, i have searched all related posts, but I am not able to find any answer to this: All versions of scanf() produce no results, and fgets() prints only the first sentence. Thanks in advance.

Answer 1

You should just use fgets() . Remember that it will keep the linefeed, so you might want to remove that manually after reading the line:

if(scanf("%d", &t) == 1)
{
  while(t > 0)
  {
    if(fgets(str, sizeof str, stdin) != NULL)
    {
      const size_t len = strlen(str);
      str[len - 1] = '\0';
      printf("You said '%s'\n", str);
      --t;
    }
    else
      printf("Read failed, weird.\n");
  }
}

Answer 2

To make it easier let's say the input is "2\\none\\ntwo\\n".

When you start your program, before the first scanf() the input buffer has all of it and points to the beginning

2\none\ntwo
^

After the first scanf() , the "2" is consumed leaving the input buffer as

2\none\ntwo
 ^^

And now you attempt to read everything but a newline ... but the first thing in the buffer is a newline, so nothing gets read.

Suggestion: always use fgets() to read full lines , and then parse the input as you think is better.

Answer 3

To use regex in C you must include regex.h . In this case, you do not need regex. Where you have "%[^\\n]" , replace it with "%s" . Make sure that you include stdio.h .