The C Programming Language, 2nd Edition, by Kernighan and Ritchie
Exercise 1.09 on page 20
Write a program to copy its input to its output, replacing each string of one or more blanks by a single blank.
Solutions by Richard Heathfield , Chris Sidi , Stig Brautaset , and Anthony Walters
#include <stdio.h> int main(void) { int c; int inspace; inspace = 0; while((c = getchar()) != EOF) { if(c == ' ') { if(inspace == 0) { inspace = 1; putchar(c); } } /* We haven't met 'else' yet, so we have to be a little clumsy */ if(c != ' ') { inspace = 0; putchar(c); } } return 0; }
Chris Sidi writes: "instead of having an "inspace" boolean, you can keep track of
the previous character and see if both the current character and previous character are spaces:"
#include <stdio.h> /* count lines in input */ int main() { int c, pc; /* c = character, pc = previous character */ /* set pc to a value that wouldn't match any character, in case this program is ever modified to get rid of multiples of other characters */ pc = EOF; while ((c = getchar()) != EOF) { if (c == ' ') if (pc != ' ') /* or if (pc != c) */ putchar(c); /* We haven't met 'else' yet, so we have to be a little clumsy */ if (c != ' ') putchar(c); pc = c; } return 0; }
Stig writes: "I am hiding behind the fact that break is mentioned
in the introduction"!
#include <stdio.h> int main(void) { int c; while ((c = getchar()) != EOF) { if (c == ' ') { putchar(c); while((c = getchar()) == ' ' && c != EOF) ; } if (c == EOF) break; /* the break keyword is mentioned * in the introduction... * */ putchar(c); } return 0; }
Here's another solution from Anthony, nut after posting it, I noticed that it looks suspiciously like Stig's solution above!
#include <stdio.h> main() { int inputchar; while((inputchar = getchar()) != EOF) { if(inputchar == ' ') { putchar(inputchar); while((inputchar = getchar()) == ' ') { /* do nothing */ } } if(inputchar != EOF) putchar(inputchar); } }
