为什么在打印一行文件时光标会转到下一行？

I have below C program to print the content of a file and to count total number of characters in it.

我在C程序下面打印文件的内容并计算其中的总字符数。

#include<stdio.h>
#include<stdlib.h>

int main()
{
    /*Declaring a FILE pointer fp.*/
    FILE *fp;
    char ch;
    int noc = 0;

    /*Using fopen() to get the address of the FILE structure, and store it in fp*/
    fp = fopen("poem.txt","r");
    if (fp == NULL)
    {
            printf("Error opening file");
            exit(1);
    }
    while(1)
    {
            ch = fgetc(fp);
            if (ch == EOF) /* EOF will be there at the end of the file.*/
                    break;
            noc++;
            printf("%c",ch); /* Printing the content of the file character by character*/
    }

    //printf("\n");

    close(fp); /* We need to fclose() the fp, because we have fopen()ed */

    printf("\tNumber of characters: %d\n",noc);

    return 0;
}

/*One interesting observation: There is an extra new line printed. Why ???*/

File poem.txt has just one line. Below is content of poem.txt

文件poem.txt只有一行。以下是poem.txt的内容

It starts with the end.

它从结束开始。

I have not hit ENTER while writing this file so it is only of one line.

我写这个文件时没有按ENTER键，所以它只有一行。

-bash-4.1$ wc poem.txt
 1  5 24 poem.txt
-bash-4.1$

You can see this is confirmed by wc (Howevr I still dont understand why wc gives number of characters as 24, instead of 23).

你可以看到这是由wc确认的（Howevr我仍然不明白为什么wc给出的字符数为24，而不是23）。

Below is the output of this program.

以下是该程序的输出。

-bash-4.1$ ./a.out
It starts with the end.
     Number of characters in this file: 24
-bash-4.1$

You can see that after printing all the characters of the file, the cursor is taken to the next line even though I have commented the printf("\n") after printing all the characters of the file .

您可以看到，在打印完文件的所有字符后，即使我在打印完文件的所有字符后注释了printf（“\ n”），光标也会转到下一行。

Why is the cursor taken to new line? I was expecting cursor to be in the same line after printing all the characters of the file, hence used a \t in the next printf.

为什么光标被带到新线？我打算在打印文件的所有字符后光标位于同一行，因此在下一个printf中使用\ t。

Also you see that my program says that number of characters is 24 (which is inline with "wc poem.txt" output).

你也看到我的程序说字符数是24（与“wc poem.txt”输出内联）。

So I am confused why is the cursor taken to new line after printing last character of the file ? Also why is total number of characters (noc) 24 and not 23 ?

所以我很困惑为什么在打印文件的最后一个字符后光标被带到新行？另外为什么总字符数（noc）24而不是23？

P.S. Although I have same question for the number of characters shown by "wc" you can ignore the "wc" outout except the number if lines. I may probably post a next question for that.

附：虽然我对“wc”显示的字符数有同样的问题，但你可以忽略“wc”outout，除了行数。我可能会发布下一个问题。

Thanks.

谢谢。

1 个解决方案

#1

Why is the cursor taken to new line?

为什么光标被带到新线？

Because the '\n' character is in the file.
因为'\ n'字符在文件中。

Also you see that my program says that number of characters is 24 (which is inline with "wc poem.txt" output).

你也看到我的程序说字符数是24（与“wc poem.txt”输出内联）。

Because the 23 characters that were printed plus the '\n' are all in the file.
因为打印的23个字符加上'\ n'都在文件中。

You can try to escape the whitespace characters to see them, since they are invisible, so something like this

您可以尝试逃避空白字符以查看它们，因为它们是不可见的，所以像这样

while ((ch = fgetc(fp)) != EOF)
{
    noc++;
    if (isspace(ch) != 0)
        printf("\\%02X", ch);
    else
        printf("%c", ch);
}

this way you will see each character, you will need to include <ctype.h>

通过这种方式，您将看到每个字符，您需要包含

Note: using break is IMHO only needed in very special situations, I don't like it because it makes hard to follow the program flow.

注意：使用break是IMHO只在非常特殊的情况下才需要，我不喜欢它，因为它很难遵循程序流程。

#1