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Learning C Language from Scratch in 2025: How to Write Your First Executable Program?

A One-Minute Quick Start Guide!

📌 Introduction: Why Does Your First C Program Always Fail to Run?Are you just learning C language, typing the code from the book, only to find compilation errors, crashes, or even a black window flashing by? Don’t panic! This article will guide you step by step to write your first truly executable C program and explain the meaning of each line of code, helping you thoroughly understand the underlying principles.

🚀 Step 1: Set Up the C Language Development Environment

1. Choose a Compiler (So Your Computer Understands C Language)

C language requires a compiler to convert the code into a machine-executable program. Recommended:

• Windows: MinGW (Download from official site) or Dev-C++ (suitable for beginners)
• Mac/Linux: The system comes with GCC (check by entering gcc --version in the terminal)

2. Install a Code Editor (Where You Write Code)

• VS Code (recommended): Lightweight, rich in plugins (install C/C++ extension)
• Clion: Professional C/C++ IDE (suitable for long-term learning)

💡 Tip: If you don’t want to deal with the environment setup, you can use an online compiler (like OnlineGDB) to run the code directly.

✍️ Step 2: Write Your First C Program

Open your editor, create a new file named hello.c, and enter the following code:

#include <stdio.h>  // Include standard input-output library

int main() {        // Main function, program execution starts here
    printf("Hello, World!\n");  // Print Hello World!
    return 0;       // Return 0 indicates normal program termination
}

📝 Line-by-Line Analysis

1. #include <stdio.h>

• Tells the compiler: “I want to use printf and scanf, which are defined in the stdio.h header file.”
• Without this line, printf will cause an error!

2. int main()

• main is the entry point of the program, like the “Start” button in a game; the operating system runs your code from here.
• int indicates that this function will eventually return an integer (usually 0 indicates success).

3. printf("Hello, World!\n");

• printf is the print function, \n represents a newline (otherwise the next output will be right next to it).
• Try removing \n, and see what happens?

4. return 0;

• Tells the operating system: “I’m done, everything is fine.”
• If it returns 1 or another value, it may indicate an error (like a file not found).

🔧 Step 3: Compile and Run

Method 1: Command Line (Recommended, Understand the Underlying Layer)

1. Open the terminal (Windows is cmd or PowerShell, Mac/Linux is Terminal).
2. Navigate to the directory where your code is located (use the cd command to change the path).
3. Enter the compilation command:
```
gcc hello.c -o hello
```

• gcc: Calls the compiler
• hello.c: Your source code file
• -o hello: The generated executable file is named hello (Windows will generate hello.exe)

4. Run the program:

./hello    # Mac/Linux
hello.exe  # Windows

✅ If you see Hello, World!, congratulations! Your first C program is running!

Method 2: One-Click Run in IDE (For the Lazy)

• In tools like VS Code, Dev-C++, just click the **”Run”** button (usually the ▶️ icon).

❌ Common Errors & Solutions

Error Message	Possible Cause	Solution
`<span>'gcc' is not recognized as an internal or external command</span>`	GCC is not installed or environment variable is not configured	Reinstall MinGW and configure PATH
`<span>undefined reference to 'printf'</span>`	Did not include `<span>#include <stdio.h></span>`	Check if the header file is missing
Black window flashes	The program closes immediately after running	Add `<span>getchar();</span>` before `<span>return 0;</span>` to pause

🎯 Advanced Challenge: Make Your Program Smarter

Try modifying the code to make the program ask the user for their name and greet them:

#include <stdio.h>

int main() {
    char name[20];  // Define a string variable to store the name
    printf("Please enter your name:");
    scanf("%s", name);  // Read user input
    printf("Hello, %s!\n", name);  // Print personalized greeting
    return 0;
}

💡 Give it a try: What happens if the name you input contains spaces (like “Zhang San Li Si”)? Why? (Hint: scanf stops reading at spaces)

📚 Summary

✅ Environment Setup: Install GCC + Code Editor✅Code Structure: #include→main()→printf→return 0✅Compile and Run: gcc hello.c -o hello→./hello✅Debugging Tips: Check error messages, add getchar() to prevent flashing 

💬 Interactive Topic: Has your first C program run successfully? What problems did you encounter? Feel free to follow and leave a message for mutual learning! 🎉

———- End ———-

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Learning C Language from Scratch in 2025: How to Write Your First Executable Program? A One-Minute Quick Start Guide!

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