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code/practise/15 编写大型程序/01 文本格式化/justify.c

@@ -0,0 +1,37 @@
+#define _CRT_SECURE_NO_WARNINGS 1
+
+#include<stdio.h>
+#include<string.h>
+#include"word.h"
+#include"line.h"
+
+#define MAX_WORD_LEN 20  //每个单词的最大长度
+
+int main(void) {
+
+	char word[MAX_WORD_LEN + 2];
+	int word_len;
+
+	clear_line();
+	for (;;) {
+		// 允许 read_word 函数多读 1 个字符，多读则代表单词长度超过 20，需要截断
+		read_word(word, MAX_WORD_LEN + 1);
+		word_len = strlen(word);
+		if (word == 0) {
+			flush_line();
+			return 0;
+		}
+		// 截断超过 20 个字符的单词
+		if (word_len > MAX_WORD_LEN)
+			word[MAX_WORD_LEN] = '*';
+		// + 1 是因为需要在上一个单词后添加空格。
+		// 如果满足条件，则需要输出当前行并清空当前行
+		if (word_len + 1 > space_remaining()) {
+			write_line();
+			clear_line();
+		}
+		add_word(word);
+	}
+
+	return 0;
+}

code/practise/15 编写大型程序/01 文本格式化/line.c

@@ -0,0 +1,63 @@
+#define _CRT_SECURE_NO_WARNINGS 1
+
+#include<stdio.h>
+#include<string.h>
+#include"line.h"
+
+#define MAX_LINE_LEN 60 // 每行的最大字符数
+
+char line[MAX_LINE_LEN + 1]; 
+int line_len = 0; // 当前行长度
+int num_words = 0; // 当前行的单词数
+
+void clear_line() {
+	
+	line[0] = '\0';
+	line_len = 0;
+	num_words = 0;
+}
+
+void add_word(const char* word) {
+
+	// 非首个单词,需要在上一个单词后添加空格
+	if (num_words > 0) {
+		line[line_len] = ' ';
+		line[line_len + 1] = '\0';
+		line_len++;
+	}
+
+	strcat(line, word);
+	line_len += strlen(word);
+	num_words++;
+}
+
+int space_remaining() {
+	
+	return MAX_LINE_LEN - line_len;
+}
+
+
+void write_line() {
+
+	int extra_space, spaces_to_insert, i, j;
+
+	extra_space = MAX_LINE_LEN - line_len; // 当前行未被填满的字符数
+	for (i = 0; i < line_len; i++) {
+		if (line[i] != ' ')
+			putchar(line[i]);
+		else {
+			spaces_to_insert = extra_space / num_words; // 遵循这个公式来增加空格
+			for (j = 0; j < spaces_to_insert; j++)
+				putchar(' ');
+			extra_space -= spaces_to_insert;
+			num_words--;
+		}
+	}
+	putchar('\n');
+}
+
+void flush_line(void) {
+
+	if (line_len > 0)
+		puts(line);
+}

code/practise/15 编写大型程序/01 文本格式化/line.h

@@ -0,0 +1,57 @@
+#ifndef LINE_H
+#define LINE_H
+
+/********************************************************
+*
+*	clear_line:	Clears the current line.
+*
+*********************************************************/
+void clear_line();
+
+
+/********************************************************
+*
+*	add_word: Adds word to the end of current line.
+*			  If this is not the first word on the line,
+*			  puts one space before word.
+*
+*********************************************************/
+void add_word(const char* word);
+
+
+/********************************************************
+*
+* space_remaining: Returns the number of characters left 
+*				   in the current line.
+*
+*********************************************************/
+int space_remaining();
+
+
+/********************************************************
+*
+* write_line: Writes the current line with justification.
+*
+*********************************************************/
+void write_line();
+
+
+/********************************************************
+*
+* flush_line: Write the current line without 
+*			  justification.If the line is empty,
+*			  does nothing.
+*
+*********************************************************/
+void flush_line(void);
+
+
+/********************************************************
+*
+*
+*
+*
+*
+*********************************************************/
+
+#endif

code/practise/15 编写大型程序/01 文本格式化/word.c

@@ -0,0 +1,33 @@
+#define _CRT_SECURE_NO_WARNINGS 1
+
+#include<stdio.h>
+#include"word.h"
+
+// 解决换行符和制表符问题
+int read_char(void) {
+
+	int ch = getchar();
+
+	if (ch == '\n' || ch == '\t')
+		return ' ';
+
+	return ch;
+}
+
+void read_word(char* word, int len) {
+
+	int ch, i;
+
+	while ((ch = read_char()) == ' ')
+		;
+
+	i = 0;
+	while (ch != ' ' && ch != EOF) {
+		if (i < len)
+			word[i++] = ch;
+
+		ch = read_char();
+	}
+
+	word[i] = '\0';
+}

code/practise/15 编写大型程序/01 文本格式化/word.h

@@ -0,0 +1,14 @@
+#ifndef WORD_H
+#define WORD_H
+
+/***********************************************************************
+*
+*	read_word: Read the next word from the input and stores it in word.
+*			   Make word empty if no word could be read because of EOF.
+*			   Truncates the word if its length exceeds len.
+*
+************************************************************************/
+
+void read_word(char* word, int len);
+
+#endif