Question

我正在尝试使用fgets读取“Danfilez.txt”的内容。但是在完成时程序返回一个随机值，我不确定为什么。我是编程新手所以非常感谢任何帮助！

int main()
{
    FILE* Danfile = fopen ("Danfilez.txt", "w");
    char fileinfo [50];// Character arrays for file data //

    if (Danfile == NULL)
    {
        printf ("ERROR\n");

    }

    else
    {
        printf("Everything works!\n");
        fprintf (Danfile, "Welcome to Dan's file."); 
        fgets(fileinfo,50,Danfile);
        printf("%s\n",fileinfo);
        fclose (Danfile); // CLOSES FILE //
    }


    return 0;
}

Answer 1

由于您要从您想要使用的文件中读取和写入＆＃34; w +＆＃34;打开文件而不仅仅是＆＃34; w＆＃34;。

但是这不会解决问题，因为一旦你写完了那个文字，你在文件中的位置仍然在最后，所以你还需要重新调整位置才能使用fseek()

阅读任何内容

fseek(Danfile,0,SEEK_SET);

Answer 2

使用 fopen（）时，您将打开选项作为参数传递给功能。这是清单：

"r"  - Opens the file for reading. The file must exist. 
"w"  - Creates an empty file for writing. If a file with the same name already exists,
      its content is erased and the file is considered as a new empty file.
"a"  - Appends to a file. Writing operations, append data at the end of the 
      file. The file is created if it does not exist.
"r+" - Opens a file to update both reading and writing. The file must exist.
"w+" - Creates an empty file for both reading and writing.
"a+" - Opens a file for reading and appending.

尝试使用“r +”或“w +”。在写完一些文字后，您在文件中的位置将随文本一起向前移动。使用快退（文件*文件名）将您的位置直接移动到文件的开头。有关文件处理的更多信息，我建议检查 stdio 库中的内容： https://www.tutorialspoint.com/c_standard_library/stdio_h.htm

如何使用fgets从文件中读取？

2 个答案: