Unexpected Chinese Characters in File Output: Debugging C File Handling

When Your C Program Writes Gibberish Instead of Text

You've just started learning C and are excited to try file handling. You write a simple program to save "Hello World" to a text file, but when you open the file, the text is replaced by strange Chinese characters. 🤯 What went wrong?

This issue can be quite frustrating, especially for beginners. It often occurs due to incorrect file handling, misused functions, or encoding problems. If your program isn't reading or writing correctly, it may interpret data in unexpected ways.

Imagine writing a note in English, but when you hand it to a friend, they read it in an entirely different language. That’s what’s happening inside your code! The problem is likely due to improper handling of file pointers or missing steps in reading the file.

In this article, we’ll break down what’s causing the issue, analyze your code, and guide you through the correct way to handle file I/O in C. By the end, you’ll be able to confidently write and read text files without unexpected surprises. 🚀

Understanding File Handling in C: Why Your Text Becomes Gibberish

When working with file I/O in C, ensuring that data is correctly written and read is crucial. The issue of text changing into Chinese characters or other unreadable symbols often arises from incorrect handling of file pointers. In the first script, we attempted to open a file, write "Hello World" into it, and then read it back. However, there was a major mistake—after writing to the file, we reopened it in read mode without properly closing the previous instance. This caused unexpected behavior because the second `fopen` call didn't store the file pointer, leading to an undefined read operation.

In the corrected approach, we ensured that every file operation follows best practices. The program first writes data using `fprintf`, then closes the file before reopening it for reading. This prevents corruption of the file pointer and ensures that data is read correctly. Another key improvement was adding error handling using `perror`. If a file operation fails, an error message is printed instead of continuing execution blindly, which could lead to data corruption or crashes. Imagine trying to write a letter but forgetting to pick up a pen—without checking for errors, the program behaves in a similarly confused manner! 🤯

We also made the program more structured by introducing separate functions for writing and reading. This makes the code modular and reusable, allowing us to debug and extend functionality easily. For example, if we later wanted to write user-inputted text instead of a hardcoded message, we could simply modify the `writeToFile` function without changing the whole program. This modular approach is like using separate compartments in a backpack—each function handles a specific task, keeping the overall program organized and efficient. 🎒

Finally, we used a `while (fgets(...))` loop to read the entire file instead of assuming a single `fgets` call would be enough. This ensures we don't miss any lines when dealing with multi-line files. The corrected program now follows proper file handling techniques, avoiding issues like garbled text and incorrect reads. By adopting structured programming and best practices, we transform unpredictable behavior into a reliable and maintainable file I/O system. 🚀

#include <stdio.h>
#include <stdlib.h>
int main() {
    FILE *fptr;
    fptr = fopen("text.txt", "w"); // Open file in write mode
    if (fptr == ) {
        perror("Error opening file");
        return 1;
    }
    fprintf(fptr, "Hello World\n"); // Write text to file
    fclose(fptr); // Close file

    fptr = fopen("text.txt", "r"); // Open file in read mode
    if (fptr == ) {
        perror("Error opening file");
        return 1;
    }

    char input[100];
    fgets(input, 100, fptr); // Read text from file
    printf("%s", input); // Print read text

    fclose(fptr); // Close file
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
void writeToFile(const char *filename, const char *text) {
    FILE *fptr = fopen(filename, "w");
    if (!fptr) {
        perror("Failed to open file");
        exit(EXIT_FAILURE);
    }
    fprintf(fptr, "%s", text);
    fclose(fptr);
}

void readFromFile(const char *filename) {
    FILE *fptr = fopen(filename, "r");
    if (!fptr) {
        perror("Failed to open file");
        exit(EXIT_FAILURE);
    }
    char buffer[100];
    while (fgets(buffer, sizeof(buffer), fptr)) {
        printf("%s", buffer);
    }
    fclose(fptr);
}

int main() {
    const char *filename = "text.txt";
    writeToFile(filename, "Hello World\n");
    readFromFile(filename);
    return 0;
}

Why Encoding Matters in File Handling

One key aspect that often causes unexpected symbols, such as Chinese characters, when writing to files in C is encoding. By default, text files are saved using a particular encoding format, which may not always match the expected one. In Windows, for example, Notepad might save files in UTF-16, while a C program typically writes in UTF-8 or ANSI. If the encoding doesn't match, the text may appear as unreadable symbols. This mismatch can be solved by explicitly setting the encoding when reading the file, ensuring compatibility between what is written and what is displayed. 📄

Another common issue is not flushing or properly closing the file before reopening it. If the file is left open in write mode and then accessed in read mode without a proper closure, the content might not be stored correctly. This can lead to unexpected results, including corrupt or misinterpreted data. Using fclose ensures that all written data is committed before the file is accessed again. Similarly, calling fflush before closing the file forces any unwritten data to be saved, preventing partial writes or unreadable content. 🛠️

Lastly, file opening modes play an important role. In C, opening a file with "w" mode overwrites existing content, while "a" mode appends to it. If a file was accidentally opened in binary mode ("wb" instead of "w"), the output could appear as unreadable characters. When handling text files, it's always recommended to use the correct mode and verify file encoding in your text editor to avoid unexpected formatting issues.