feat hectic C: logger log in file

package/c/hectic/examples/file_logging_example.c

@@ -0,0 +1,52 @@
+/**
+ * File Logging Example for Hectic Library
+ * 
+ * This example demonstrates how to use the file logging capabilities
+ * of the Hectic library, showing both programmatic configuration
+ * and environment variable-based configuration.
+ */
+
+#include "../hectic.h"
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+    // Initialize the logger
+    logger_init();
+    
+    // Log a message to stderr
+    raise_info("Starting file logging example");
+    
+    // Enable file logging programmatically
+    const char *log_file = "example_log.txt";
+    if (logger_set_file(log_file) != 0) {
+        raise_exception("Failed to open log file: %s", log_file);
+        return 1;
+    }
+    
+    // Set output mode to write to both stderr and file
+    logger_set_output_mode(LOG_OUTPUT_BOTH);
+    
+    // Log messages at different levels
+    raise_debug("This is a debug message");
+    raise_info("This is an info message");
+    raise_notice("This is a notice message");
+    raise_warn("This is a warning message");
+    raise_exception("This is an exception message");
+    
+    // Switch to file-only mode
+    logger_set_output_mode(LOG_OUTPUT_FILE_ONLY);
+    raise_info("This message will only appear in the log file");
+    
+    // Switch back to stderr-only mode
+    logger_set_output_mode(LOG_OUTPUT_STDERR_ONLY);
+    raise_info("This message will only appear on stderr");
+    
+    // Clean up
+    logger_free();
+    
+    printf("\nLog file demonstration complete. Check %s for logged messages.\n", log_file);
+    printf("\nYou can also run this program with environment variables:\n");
+    printf("  LOG_FILE=custom.log LOG_OUTPUT_MODE=BOTH LOG_LEVEL=DEBUG ./file_logging_example\n");
+    
+    return 0;
+}