Write a program to copy its input to its output, replacing each string of one or more blanks by a single blank.
编写这样一个程序，实现将输入流复制到输出流，但是要将输入流中多个空格过滤成一个空格。
1.旗帜变量方法
#include <stdio.h> int main(void) { int c; int inspace;
//这里用了旗帜变量来过滤多余空格 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; }
2.保存上一个输入字符
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:"
Chris Sidi 写道：“我们可以不用‘inspace’这样一个布尔型旗帜变量，通过跟踪判断上一个接收字符是否为空格来进行过滤。”
#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; }
3.利用循环进行过滤
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; }
本文转自二郎三郎博客园博客，原文链接：http://www.cnblogs.com/haore147/p/3647917.html，如需转载请自行联系原作者
