Syntax of command line arguments - Mini Project: Build & Apply

Syntax of command line arguments

📖 Scenario: You want to create a simple C program that reads command line arguments to greet a user by name.

🎯 Goal: Build a C program that accepts a name as a command line argument and prints a greeting message using that name.

📋 What You'll Learn

Create the main function with parameters int argc and char *argv[]

Check if the user has provided exactly one command line argument (excluding the program name)

Print a greeting message using the provided name

Print an error message if no name is provided

💡 Why This Matters

🌍 Real World

Many programs use command line arguments to customize their behavior without changing the code.

💼 Career

Understanding command line arguments is essential for software developers, especially when creating tools and utilities.

1

Create the main function with command line arguments

Write the main function header with parameters int argc and char *argv[].

C

int main(int argc, char *argv[]) {
    // Your code here
    return 0;
}

Need a hint?

The main function should accept two parameters: argc and argv.

2

Check if exactly one argument is provided

Inside the main function, write an if statement to check if argc is equal to 2.

C

int main(int argc, char *argv[]) {
    // Check if argc is 2
    if (argc == 2) {
        // Your code here
    }
    return 0;
}

Need a hint?

Remember, argc counts the program name as the first argument, so the user name is the second argument.

3

Print greeting message using the argument

Inside the if (argc == 2) block, write a printf statement to print Hello, <name>! where <name> is argv[1].

C

int main(int argc, char *argv[]) {
    if (argc == 2) {
        // Print greeting with argv[1]
        // Your code here
    }
    return 0;
}

Need a hint?

Use printf with the format specifier %s to print the string argument.

4

Print error message if no name is provided

Add an else block after the if to print Please provide your name as a command line argument. using printf.

C

int main(int argc, char *argv[]) {
    if (argc == 2) {
        printf("Hello, %s!\n", argv[1]);
    } else {
        // Print error message
        // Your code here
    }
    return 0;
}

Need a hint?

The else block runs when the user does not provide exactly one argument.