Question

here is the problem
for example

in = "a    b\nab  c\ndd";
out = "a b\nb c\ndd"
Here is my C code

while(c=getchar()!=EOF){
  if(c==' '){
      while( (c1=getchar()) == ' '); // ignore all other contiguous blank
      putchar(c); // output one blank
      putchar(c1);  // output the next non-blank character             
  }
  else putchar(c);
}

Can I have an implementation with shrinked size?

Answer 1

Assuming you remove only ' ' :

int c;
char space_found = 0;

while ( ( c = getchar() ) != EOF) {
   if ( (!space_found) || (c != ' ') ) { // if the previous is not a space, or this is not a space
       putchar(c);
   }
   space_found = (c == ' '); // (un)set the flag
}

You can change it to check for any white space with a simple macro:

#define is_white_space(X) ( ( (X) == ' ' ) || ( (X) == '\t' ) || ( (X) == '\n' ) )

and replace the c == ' ' with it