Linux C: 使用 fwrite 将字符写入不同的行
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C: use fwrite to write char to different line
提问by Jake
I have to write to a file as follows:
我必须按如下方式写入文件：
A
B
C
D
...
Each character of the alphabet needs to be written to different line in the file. I have the following program which writes characters one after another:
字母表的每个字符都需要写入文件中的不同行。我有以下程序一个接一个地写字符：
FILE* fp;
fp = fopen("file1","a+");
int i;
char ch= 'A';
for(i=0; i<26; i++){
fwrite(&ch, sizeof(char), 1, fp);
ch++;
}
fclose(fp);
How should I change the above program to write each character to a new line. (I tried writing "\n" after each character, but when I view the file using VI editor or ghex tool, I see extra characters; I am looking for a way so that vi editor will show file exactly as shown above).
我应该如何更改上述程序以将每个字符写入新行。（我尝试在每个字符后写入“\n”，但是当我使用 VI 编辑器或 ghex 工具查看文件时，我看到了额外的字符；我正在寻找一种方法，以便 vi 编辑器能够完全如上所示显示文件）。
I tried using the following after first fwrite:
我在第一次 fwrite 后尝试使用以下内容：
fwrite("\n", sizeof("\n"), 1, fp);
Thanks.
谢谢。
采纳答案by dasblinkenlight
fwrite("\n", sizeof("\n"), 1, fp);
should be
应该
fwrite("\n", sizeof(char), 1, fp);
Otherwise, you are writing an extra \0that is part of zero-termination of your "\n"string constant (sizeof("\n")is two, not one).
否则，您正在编写一个额外\0的"\n"字符串常量零终止的一部分（sizeof("\n")是两个，而不是一个）。
回答by Jim Mischel
What "extra characters" do you see? You do realize that the "a+"parameter to fopenopens the file for appending, so that you're writing to the end of the file. Did you perhaps mean "w+", which will overwrite the file?
你看到了什么“额外字符”？您确实意识到打开文件以进行追加的"a+"参数fopen，因此您正在写入文件的末尾。您可能是说"w+"，这会覆盖文件吗？
You could use:
你可以使用：
fputc((int)ch, fp);
fputc((int)'\n', fp);
Or even fprintf(fp, "%c\n", ch);
甚至 fprintf(fp, "%c\n", ch);
