How to eliminate extra whitespaces?

[dat]

How do I make many consecutive white spaces into one white space? I tried this:

	int c, last_c = '\0';
	
	while( (c=getchar()) != EOF ){
		if( !isspace(c) && isspace(last_c) )
			putchar(' ');
		if( !isspace(c) ) 
			putchar(c);
		
		last_c = c;
	}

which works, but is it the most efficient way to write it? Or is there at least a better way of doing this?

[Prelude]

>but is it the most efficient way to write it?
Most of the time it doesn't matter if your method is the most efficient, just make sure it's simple enough to understand and don't worry about performance unless there is a real bottleneck. Here is another way to do it:

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

int main ( void )
{
  int ch;

  while ( ( ch = getchar() ) != EOF ) {
    if ( isspace ( ch ) ) {
      while ( isspace ( ch ) && ( ch = getchar() ) != EOF )
        ; /* Eat whitespace */

      putchar ( ' ' );
    }

    putchar ( ch );
  }

  return 0;
}

-Prelude