练习1-18在K＆放大器; R C程序设计语言 [英] Exercise 1-18 in K&R The C Programming Language
问题描述
本练习快把我逼疯了。很抱歉，如果我的编程问题显得小气，但我是一个新手，所以请多多包涵。
演习要求如下：
编写一个程序，删除输入的每一行尾随空格和制表符，并删除全部空行。
谁能告诉我为什么我的code不起作用？我还没有解决的完全空白行的问题，但我找不到任何理由，为什么我的code不会删除尾随空格和制表符。在这里，它是：
的#include＆LT;＆stdio.h中GT;＃定义MAXLINE 1000INT better_line_length（焦线[]，INT LIM）;
无效副本（字符为[]，在[]字符）;INT主要（无效）
{
INT LEN;
个char [MAXLINE]
焦炭better_s [MAXLINE] 而（（LEN = better_line_length（S，MAXLINE））大于0）{
副本（better_s，S）;
的printf（％S \\ n，better_s）;
} 返回0;
}INT better_line_length（char中[]，INT LIM）
{
INT C，I，last_letter; 对于（i = 0; I＆LT; LIM - 1安培;及（C =的getchar（））= EOF和放大器;和C ='\\ n'; ++我！）{
S [i] = C;
如果（C =！＆放大器;和C =！'\\ T'）
last_letter = I;
} S [last_letter + 1] ='\\ 0'; 返回last_letter + 1;
}无效副本（字符为[]，在[]字符）
{
INT I = 0; 而（（在[I] =从[I]）！='\\ 0'）
++我;
}
例如，我希望code的工作如下：如果我的输入是这样的（其中▯表示空格）：
abcdefg▯▯▯▯▯▯▯▯▯▯▯▯
我希望可以将输出为
ABCDEFG
请注意，有没有空格预期输出后。
但相反，输出我得到的是输入的第一个字符的无限打印。
更新：我的code工作时，输入与键盘作为预期，但我仍然可以当输入来自另一个文件中获取一个字符的重复。我的心被烧断。
问题是你的code的这一部分：
，而（（LEN = better_line_length（S，MAXLINE））0）{
副本（better_s，S）;
的printf（％S \\ n，better_s）;
}
这无限迭代为（LEN = better_line_length（S，MAXLINE））将始终大于0（字符串至少有1个字符）。<结果/ p>
您不需要，而循环。相反，像这样做：
LEN = better_line_length（S，MAXLINE）;
副本（better_s，S）;
的printf（％S | \\ n，better_s）;
（也请注意，您不使用 LEN 的任何地方）
This exercise is driving me crazy. Sorry if my programming problems seem petty, but I'm a beginner so please bear with me.
The exercise asks for the following: Write a program to remove trailing blanks and tabs from each line of input, and to delete entirely blank lines.
Can anybody tell me why my code doesn't work? I haven't yet tackled the issue of entirely blank lines, but I can't find any reason why my code won't remove trailing blanks and tabs. Here it is:
#include <stdio.h>
#define MAXLINE 1000
int better_line_length(char line[], int lim);
void copy(char to[], char from[]);
int main(void)
{
int len;
char s[MAXLINE];
char better_s[MAXLINE];
while ((len = better_line_length(s, MAXLINE)) > 0) {
copy(better_s, s);
printf("%s\n", better_s);
}
return 0;
}
int better_line_length(char s[], int lim)
{
int c, i, last_letter;
for (i = 0; i < lim - 1 && (c = getchar()) != EOF && c != '\n'; ++i) {
s[i] = c;
if (c != ' ' && c != '\t')
last_letter = i;
}
s[last_letter+1] = '\0';
return last_letter+1;
}
void copy(char to[], char from[])
{
int i = 0;
while ((to[i] = from[i]) != '\0')
++i;
}
For example, I expect the code to work as follows: If my input is like this (where '▯' indicates a space):
abcdefg▯▯▯▯▯▯▯▯▯▯▯▯
I expect the output to be
abcdefg
Notice that there are no spaces after the expected output.
But instead, the output I get is an infinite printing of the first character of the input.
UPDATE: My code works as expected when input is taken from the keyboard, but I still get the repeating of one character when input is taken from another file. My mind is blown.
The problem is this part of your code:
while ((len = better_line_length(s, MAXLINE)) > 0) {
copy(better_s, s);
printf("%s\n", better_s);
}
It iterates infinitely as the result of (len = better_line_length(s, MAXLINE)) will always be greater than 0 (for strings with at least 1 character).
You do not need a while loop. Instead, do it like this:
len = better_line_length(s, MAXLINE);
copy(better_s, s);
printf("%s|\n", better_s);
(also note that you don't use len anywhere)
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