Learn Declaration, Type and Return

From our previous lesson, you learned the basic anatomy of functions:

main.c


              123456
            
func_type func_name(arguments_placeholder)
{
	// The core functionality of the function
	// The resulting outcome after function execution
	return function_output; 
}

Declaration

Before utilizing a function, it has to be declared. Calling a function before its declaration will result in an error.

You can either declare the entire function simultaneously with its definition (as illustrated above) or use a prototype, which we'll touch upon as a bonus at the end of this segment.

Function Types and Return Values

The function's type informs the compiler about the datatype of the function's outcome. For instance, if our function calculates the sum of two integers, then we anticipate an integer as the result.

main.c


              12345678
            
int sumFunction()
{
	int number1 = 6;
	int number2 = 10;
	int result = number1 + number2;

	return result;
}

A mismatch between the data type and the return type might render the function (or even the whole program) malfunctioning.

main.c


              12345678
            
int sumFunction()
{
	double number1 = 6.985;
	double number2 = 231.465;
	double result = number1 + number2;

	return result; // This will lead to an incorrect result
}

When summing non-integer values, you'd expect a precise outcome. But due to the type inconsistency, the result is erroneous.

main.c


              1234567891011121314151617
            
#include <stdio.h> 

int func()
{
	double number1 = 6.985;   // Not `int` nubmer
	double number2 = 231.765; // Not `int` number
	double result = number1 + number2;

	return result; // Output of function
}

int main() {
    // Call and immediately printing the result of our function
	printf("Expected Result is 238.75, but result is %d\n", func());

	return 0;
}

Two primary factors contribute to this error:

An incorrect return type (should be double);
Using the wrong format specifier (%d) in the printf() function (should be %f).

The correct version would be:

main.c


              1234567891011121314151617
            
#include <stdio.h> 

double func()
{
	double number1 = 6.985; // `int` nubmer
	double number2 = 231.765; // `int` number
	double result = number1 + number2;

	return result; // Output of function
}

int main() {
	// Print the result of our function
	printf("Expected Result is 238.75, and result is %f\n", func());

	return 0;
}

This implies that we can directly assign the function's result to variables/arrays or even pass it to other functions. An example of this is how we used the result with the printf function in the scenarios above.

Note

The format specifier for floating-point numbers is %f.

It's also worth mentioning that a function can house multiple return statements, with each activating under distinct conditions.

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Thanks for your feedback!

Section 5. Chapter 2

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From our previous lesson, you learned the basic anatomy of functions:

main.c


              123456
            
func_type func_name(arguments_placeholder)
{
	// The core functionality of the function
	// The resulting outcome after function execution
	return function_output; 
}

Declaration

Before utilizing a function, it has to be declared. Calling a function before its declaration will result in an error.

You can either declare the entire function simultaneously with its definition (as illustrated above) or use a prototype, which we'll touch upon as a bonus at the end of this segment.

Function Types and Return Values

main.c


              12345678
            
int sumFunction()
{
	int number1 = 6;
	int number2 = 10;
	int result = number1 + number2;

	return result;
}

A mismatch between the data type and the return type might render the function (or even the whole program) malfunctioning.

main.c


              12345678
            
int sumFunction()
{
	double number1 = 6.985;
	double number2 = 231.465;
	double result = number1 + number2;

	return result; // This will lead to an incorrect result
}

When summing non-integer values, you'd expect a precise outcome. But due to the type inconsistency, the result is erroneous.

main.c


              1234567891011121314151617
            
#include <stdio.h> 

int func()
{
	double number1 = 6.985;   // Not `int` nubmer
	double number2 = 231.765; // Not `int` number
	double result = number1 + number2;

	return result; // Output of function
}

int main() {
    // Call and immediately printing the result of our function
	printf("Expected Result is 238.75, but result is %d\n", func());

	return 0;
}

Two primary factors contribute to this error:

An incorrect return type (should be double);
Using the wrong format specifier (%d) in the printf() function (should be %f).

The correct version would be:

main.c


              1234567891011121314151617
            
#include <stdio.h> 

double func()
{
	double number1 = 6.985; // `int` nubmer
	double number2 = 231.765; // `int` number
	double result = number1 + number2;

	return result; // Output of function
}

int main() {
	// Print the result of our function
	printf("Expected Result is 238.75, and result is %f\n", func());

	return 0;
}

Note

The format specifier for floating-point numbers is %f.

It's also worth mentioning that a function can house multiple return statements, with each activating under distinct conditions.

Everything was clear?

Thanks for your feedback!

Section 5. Chapter 2