The truth behind the C language file operation problem

The truth about file operation problems: file opening failed: insufficient permissions, wrong paths, and file occupied. Data writing failed: the buffer is full, the file is not writable, and the disk space is insufficient. Other FAQs: slow file traversal, incorrect text file encoding, and binary file reading errors.

The truth behind the C language file operation problem

When processing files in C language, you often encounter various difficulties. From file opening failures to data writing errors, these issues can be overwhelming. This article will reveal the truth behind these puzzles and provide tangible and reliable solutions.

File opening failed

fopen() function is used to open a file. If the file does not exist or is inaccessible, the function returns a null pointer. Here are some reasons that may cause this problem:

• Insufficient permissions: Make sure you have the necessary permissions to open the file (such as read and write).
• Path Error: Double-check the path of the file for syntax or spelling errors.
• File occupied: fopen() may fail if another program is using the file. Try opening the file again with a different access mode, such as fopen("file.txt", "w") .

Code example:

 FILE *fptr;

if ((fptr = fopen("file.txt", "r")) == NULL) {
  printf("File opening failed!\n");
  return;
}

Data writing failed

When writing data to a file using the fwrite() function, you may encounter the following problems:

• Buffer full: The buffer is a temporary storage area used to store data to be written to the file. If the buffer is full, fwrite() will fail. Forced flushing data to disk using the fflush() function solves this problem.
• File not writable: Make sure that the file has appropriate permissions and is not locked by other programs.
• Insufficient disk space: Check if there is enough disk space to store data.

Code example:

 char data[] = "Hello, world!";
size_t data_len = strlen(data);

if (fwrite(data, 1, data_len, fptr) != data_len) {
  printf("Data writing failed!\n");
  return;
}

fflush(fptr);

Other FAQs

In addition to file opening and writing failures, there are some other common difficulties:

• File traversal is slow: Use fseek() and ftell() functions to improve file traversal efficiency.
• Text file encoding: Set the correct text encoding based on the file content, such as UTF-8 or ASCII.
• Binary file reading: Open the file in binary mode to read and write binary data.

By understanding the reasons behind these difficulties, you can easily solve C file operation problems. Always double-check error messages and use debugging tools to identify the source of the problem.

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