尝试验证它是否存在后，换行符删除不起作用 [英] Newline removal not working after trying to verify it exists

问题描述

我正在编写代码来解析一些输入数据并以特殊格式将其写入文件.我正在从每个字符串标记中删除一个换行符:

I am making a code to parse some input data and write it to a file in a special formatting. I am removing a newline from each string token as so:

token[strlen(token)-2] ='\0'

它是 -2 因为最后一个元素是 \0.这非常有效.但是，输入数据的最后一个元素没有换行符，因此仅使用它最终会从最后一个输入集中删除倒数第二个字符.

It is -2 because the last element is \0. This much works. However, the final element of the input data does NOT have a newline, so using just that ends up removing the second-to-last character from the last input set.

original input: 0.38
after running it through the removal: 0.3

显而易见的解决方案是在删除之前检查换行符是否存在.我这样做:

The obvious solution is to check if the newline is there before removing. I do this:

if(token[strlen(token)-2] =='\n') token[strlen(token)-2] ='\0';

但是，添加了 if 子句后，换行符就不再去掉了！我究竟做错了什么?来自整个代码的片段:

However, after adding the if clause, the newline is no longer removed! What am i doing wrong? Snippit from the whole code:

    while((token = strsep(&line, ",")) != NULL){
        if(x++ == 1){
            fwrite("    <item>\n", 11, 1, fw);
            fwrite("        <name>", 14, 1, fw);
            fwrite(token, strlen(token), 1, fw);
            fwrite("</name>\n", 8, 1, fw);
        }
        else if(isdigit(token[0])) {
            if(token[strlen(token)-2] =='\n') token[strlen(token)-2] ='\0';
            fwrite("        <SPC>", 13, 1, fw);
            fwrite(token, strlen(token), 1, fw);
            fwrite("</SPC>\n", 7, 1, fw);
            fwrite("    </item>\n", 12, 1, fw);
        }
    }

推荐答案

你的换行符应该在 line[strlen(line)-1]，但你可以在 Windows 下工作，其中换行符实际上包含回车符后跟换行符.这将解释为什么 line[strlen(line)-2]='\0' 成功删除行尾，但测试失败.

Your newline should be at line[strlen(line)-1], but you may work under Windows where a newline actually consists of a carriage return followed by a newline. This would explain why line[strlen(line)-2]='\0' is successful in removing the end-of-line, but the test fails.

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