#include <stdio.h> #define NOT_BLANK 1 #define BLANK 0 main() { int c; int last_ch = NOT_BLANK; while ((c=getchar()) != EOF){ if (c == ' ' || c == ' ' || c == ' '){ if (last_ch == NOT_BLANK) putchar(' '); last_ch = BLANK;//这条语句可以包括在最近的if里面 }else{ putchar(c); last_ch = NOT_BLANK; } } }