Predefined macros - Mini Project: Build & Apply

Using Predefined Macros in C

📖 Scenario: You are writing a simple C program that needs to display information about when and where it was compiled. This is useful for debugging and tracking versions.

🎯 Goal: Build a C program that uses predefined macros to show the current date, time, and file name of the source code.

📋 What You'll Learn

Use the predefined macro __DATE__ to get the compilation date

Use the predefined macro __TIME__ to get the compilation time

Use the predefined macro __FILE__ to get the source file name

Print these values clearly labeled

💡 Why This Matters

🌍 Real World

Developers often use predefined macros to embed build information in programs for debugging and version tracking.

💼 Career

Knowing how to use predefined macros is useful for software developers working on C projects, especially in embedded systems and system programming.

1

Create a C program skeleton

Write the initial C program with #include <stdio.h> and an empty main function that returns 0.

C

#include 

int main() {
    // Your code here
    return 0;
}

Need a hint?

Start by including the standard input-output header and create the main function.

2

Add variables for predefined macros

Inside main, create three const char* variables named compile_date, compile_time, and source_file. Assign them the values __DATE__, __TIME__, and __FILE__ respectively.

C

#include 

int main() {
    // Your code here
    return 0;
}

Need a hint?

Use the predefined macros exactly as shown to assign the variables.

3

Print the predefined macro values

Use printf to display the labels and values of compile_date, compile_time, and source_file on separate lines.

C

#include 

int main() {
    const char* compile_date = __DATE__;
    const char* compile_time = __TIME__;
    const char* source_file = __FILE__;
    // Your code here
    return 0;
}

Need a hint?

Use printf with %s to print each string variable with a label.

4

Run and display the output

Run the program and print the output showing the compilation date, time, and source file name.

C

#include 

int main() {
    const char* compile_date = __DATE__;
    const char* compile_time = __TIME__;
    const char* source_file = __FILE__;
    printf("Compilation Date: %s\n", compile_date);
    printf("Compilation Time: %s\n", compile_time);
    printf("Source File: %s\n", source_file);
    // Your code here
    return 0;
}

Need a hint?

Run the program to see the compilation details printed.