C Tutorial

💻 Function Arguments in C

Function arguments (also known as parameters) are the values passed to functions when they are called. They allow functions to process input data and return output. In C, you can pass arguments to a function by value or by reference.

🔄 Syntax of Function Arguments

The syntax for function arguments is defined in the function declaration and definition. Arguments are enclosed in parentheses after the function name.

return_type function_name(argument1, argument2, ...) {
    // Function body
    return value; // optional
}
  

Here, argument1, argument2, ... are the parameters that the function takes as input when it is called.

🔧 Example: Function with Arguments

#include 

// Function declaration with arguments
void add(int a, int b) {
    printf("Sum: %d\n", a + b);
}

int main() {
    int x = 5, y = 3;
    add(x, y); // Calling function with arguments
    return 0;
}
  

📌 Types of Function Arguments

Function arguments can be categorized into two types:

1. Pass by Value

In pass-by-value, the actual value of the argument is passed to the function. Changes made to the argument inside the function do not affect the original value.

#include 

void updateValue(int num) {
    num = num * 2; // This change will not affect the original variable in main
    printf("Updated value inside function: %d\n", num);
}

int main() {
    int a = 10;
    updateValue(a);
    printf("Original value in main: %d\n", a); // Output will still be 10
    return 0;
}
  

2. Pass by Reference

In pass-by-reference, instead of passing the actual value, the address (or reference) of the variable is passed to the function. Changes made to the argument inside the function will affect the original value.

#include 

void updateValue(int *num) {
    *num = *num * 2; // Changes will affect the original variable in main
    printf("Updated value inside function: %d\n", *num);
}

int main() {
    int a = 10;
    updateValue(&a); // Passing the address of a
    printf("Original value in main: %d\n", a); // Output will be 20
    return 0;
}
  

🔧 Default Arguments

In C, you cannot specify default values for function arguments directly, unlike some other programming languages. However, you can use function overloading (not directly supported in C but achievable through different function names or macros) or use variable-length arguments (variadic functions).

💡 Key Points to Remember

• In pass-by-value, the function gets a copy of the argument, and any changes made to it inside the function do not affect the original variable.
• In pass-by-reference, the function gets the address of the argument, and any changes made to it will affect the original variable.
• Function arguments help in making the code modular and reusable.
• When passing arrays or large structures, it is common to use pass-by-reference to avoid unnecessary copying of data.

📝 Try It Yourself!

❌ Common Mistakes

• 🚫 Forgetting to use the & operator when passing variables by reference (e.g., &a for a variable a).
• 🚫 Confusing pass-by-value and pass-by-reference and expecting the same behavior from both.
• 🚫 Passing an incorrect type of argument to the function, leading to type mismatch errors.