将空格串替换为最少数量的制表符和空格
程序代码:
#include <stdio.h> #define TABSTOP 4 int main(void) { size_t spaces = 0; int ch; size_t x = 0; /* position in the line */ size_t tabstop = TABSTOP; /* get this from the command-line * if you want to */ while ((ch = getchar()) != EOF) { if (ch == ' ') { spaces++; } else if (spaces == 0) /* no space, just printing */ { putchar(ch); x++; } else if (spaces == 1) /* just one space, never print a tab */ { putchar(' '); putchar(ch); x += 2; spaces = 0; } else { while (x / tabstop != (x + spaces) / tabstop) /* are the spaces reaching behind the next tabstop ? */ { putchar('\t'); x++; spaces--; while (x % tabstop != 0) { x++; spaces--; } } while (spaces > 0) /* the remaining ones are real space */ { putchar(' '); x++; spaces--; } putchar(ch); /* now print the non-space char */ x++; } if (ch == '\n') { x = 0; /* reset line position */ } } return 0; } 这个程序不太理解,具体怎么实现?