C Calling Functions

📞 C Calling Functions – How to Call a Function in C

In C programming, a function call means executing a function that’s been defined elsewhere in your code. You “call” a function by using its name followed by parentheses, and passing arguments (if any).

🔹 Function Call Basics

When a function is called, the control jumps to its definition, executes the code, and then returns back to the point where it was called.

📝 Example 1: Calling a Simple Function

Here we call the greet() function from inside the main() function.

#include <stdio.h>

// Function declaration
void greet();

int main() {
    greet(); // Function call
    return 0;
}

// Function definition
void greet() {
    printf("Hello, C Learner!\n");
}
  

📝 Example 2: Calling a Function with Parameters

This function takes an argument and uses it in its output.

#include <stdio.h>

// Function declaration
void greetUser(char name[]);

int main() {
    greetUser("Alice"); // Function call with argument
    return 0;
}

// Function definition
void greetUser(char name[]) {
    printf("Hello, %s!\n", name);
}
  

📝 Example 3: Calling a Function That Returns a Value

This function returns an integer result back to the calling function.

#include <stdio.h>

// Function declaration
int square(int num);

int main() {
    int result = square(5); // Function call with value returned
    printf("Square: %d\n", result);
    return 0;
}

// Function definition
int square(int num) {
    return num * num;
}
  

💡 Tips

• Always declare the function before calling it (unless it’s already defined above the call).
• Match the number and type of arguments when calling a function.
• You can reuse a function as many times as needed by calling it multiple times!

🎯 Summary

• Use function calls to execute reusable blocks of code.
• Functions can take arguments and return values.
• They improve readability, maintainability, and structure of your code.

🚀 Ready to Explore?

Try modifying the function calls to pass different values and experiment with the results. Functions are like magic spells—call them right and they do the work!