How do I check if the previous 2 getchars were a space?

Question

My code reads a textfile or input from the terminal and prints out the message but with each word on a new line the code below works with the exception of double or more spaces.

Because I use the space as an indication that a whole word has ended. But I don't want a space to be printed as a blank separate line. Any help would be appreciated!!

A sample input would be:

Hello world this is great

The current output is:

Hello
world
this
is
great

The problem is if the input includes a sentence with two or more spaces it prints a blank line. I want the code to skip to the next word.

for instance

input: hello world  how are 
                  ^^(two spaces)
output:
hello
world
        < (I want this gap gone)
how
are


#include <ctype.h>
#include <stdio.h>
#include <unistd.h>

int main()
{
    int c;                          //next character



    while (1) {
        c = getchar();
        if (c == EOF){ break; }  // Exit the loop if we receive EOF ("end of file")
        if (ispunct(c)|| isdigit(c) || c== '\n') //ignores numbers and punnctuation
            continue;



        if (isspace(c)) {   // if there is a space end of word has been reach output the word
            printf("\n");
            continue;

        }
        usleep(200000); // delay between each word
        putchar(c);

    }
}

On a couple of unrelated notes: The continue statement will continue the loop immediately, the fflush(stdout) call after it will not be executed. Not that you really need it because output to stdout (which is where printf is writing) is by default line-buffered, so that printf("\n") call will include flushing the output buffer of stdout. — Some programmer dude
More related to your question, please edit it to include some sample input, and the output you expect from that input. Also please take some time to read How to Ask, as well as this question checklist. — Some programmer dude

linuxfan says Reinstate Monica linuxfan says Reinstate Monica · Accepted Answer · 2020-04-09T05:11:22

What you need is one more variable to remember what the previous character was, so you can distinguish a word ending and skip further separators until a new word is encountered.

In the fragment below I called that variable "pcwaswsp". The code is copied from yours, with two modifications: 1) the new variable and 2) I moved the check for words just after the reading.

int c;         // current character
int pcwassp;  // "previous character was space"

pcwassp = 0;  // previous char is not a space

while (1) {
  c = getchar();
  if (c == EOF) break;  // no more data
  // optional: if (pcwassp==2) pcwassp=isspace(c);

  // word separation
  if (isspace(c)) {
    if (!pcwassp)
      printf("\n");   // break line only on new word separator
    pcwassp = 1;      // ...but this char IS a space
    continue;
  } // else...

  pcwassp=0;   // ...else, this char is not a space

  //ignores numbers and punctuation
  ...
}

This code would print a new line if its input starts with a separator. To correct this, the variable pcwassp could be initialized to a special value (not 0 and not 1) having the meaning of "first time". The in the cycle, only the first time, this variable can be set to "previous char was a separator" (if the current char is a space) in order to prevent the first line output to be empty.

How do I check if the previous 2 getchars were a space?

1 Answers