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C Basics
course content

Course Content

C Basics

C Basics

1. Introduction
Structure of the C-ProgramEssentials of C ProgramHow to Run the Program?
2. Data
DataVariablesPrintfIntroduction to ArraysTwo Dimensional ArraysChar and StringSizeofPrintf PracticeSizeof Practice
3. Operators
Assignment, Comparison, Not Equal ToSum, Difference, Increment, DecrementMultiplication, Division and ModuloComparison OperatorsComparison Operators PracticeLogical OperatorsLogical Operators Practice
4. Control Statements
If-else Operatorif-else Operator PracticeTernary OperatorSwitch, BreakWhile, Do-WhileFor, ContinueFor Loop Practice
5. Functions
Structure of the FunctionDeclaration, Type and ReturnArgumentsPassing ArgumentsHeader, Prototypes Void, Recursion
6. Pointers
Pointers are around UsReferences and DereferencesPointersMalloc and FreeFunctions, Arrays and Two PointersVoid

book
Void, Recursion

The void Return Type in C

In the C programming language, functions that are declared with a specific return type are expected to have a return statement, delivering a value matching that type. However, there are scenarios where a function doesn't need to return anything – perhaps it's simply displaying text on the screen. For such instances, the function should be declared with the void type.

c

Main

copy

              
12345678910111213

            
#include <stdio.h>

void func()
{
    printf("This function returns nothing\n");
}

int main()
{
    func();

    return 0;
}

The void keyword specifies that a function doesn't return a value, and it can also be used in the context of pointers. Attempting to declare a variable of type void will result in an error because the compiler won't understand how much memory to allocate.

Here's an intentional error for illustration.

c

Main

copy

              
12345678

            
#include <stdio.h>

int main()
{
    void variable;

    return 0;
}

Delving into Recursion

C supports the ability for a function to call itself, a technique known as recursion.

Imagine recursion as the action of stretching and then releasing a rubber band. It's commonly leveraged in mathematical operations, such as calculating factorials.

For instance: 3! = 3 x 2 x 1

Factorials are often utilized in approximating function values by expanding these functions into Taylor or Maclaurin series.

Note

This chapter's inspiration came right after the author completed a lab assignment at a university. The task was to approximate the cotangent value to a certain precision by expanding it into a Taylor series. And naturally, the factorial computation was indispensable.

c

Main

copy

              
1234567891011121314151617181920

            
#include <stdio.h>

int factorial(int n) 
{
    // if n = 0 or 1, because 0! = 1 and 1! = 1
    if (n == 0 || n == 1)
        return 1;
    // recursion case
    else
        return n * factorial(n - 1);
}

int main()
{
    int n = 3;

    printf("factorial(%d) = %d\n", n, factorial(n));

    return 0;
}

In the context of recursion, the function will continue to call itself until it meets the condition n == 0 || n == 1. Once this condition is satisfied, the results from the subsequent factorial() function calls are returned in the reverse order, similar to folding an accordion. By the time step 6 is reached, the initial call to factorial(3) will return 6.

question mark

Imagine an ad where you see a girl holding a bottle of milk. On this bottle, there's another picture of the same girl holding a bottle of milk, and on that smaller bottle, there's yet another picture of the girl, and so on. What's this concept called?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 5. ChapterΒ 6

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course content

Course Content

C Basics

C Basics

1. Introduction
Structure of the C-ProgramEssentials of C ProgramHow to Run the Program?
2. Data
DataVariablesPrintfIntroduction to ArraysTwo Dimensional ArraysChar and StringSizeofPrintf PracticeSizeof Practice
3. Operators
Assignment, Comparison, Not Equal ToSum, Difference, Increment, DecrementMultiplication, Division and ModuloComparison OperatorsComparison Operators PracticeLogical OperatorsLogical Operators Practice
4. Control Statements
If-else Operatorif-else Operator PracticeTernary OperatorSwitch, BreakWhile, Do-WhileFor, ContinueFor Loop Practice
5. Functions
Structure of the FunctionDeclaration, Type and ReturnArgumentsPassing ArgumentsHeader, Prototypes Void, Recursion
6. Pointers
Pointers are around UsReferences and DereferencesPointersMalloc and FreeFunctions, Arrays and Two PointersVoid

book
Void, Recursion

The void Return Type in C

In the C programming language, functions that are declared with a specific return type are expected to have a return statement, delivering a value matching that type. However, there are scenarios where a function doesn't need to return anything – perhaps it's simply displaying text on the screen. For such instances, the function should be declared with the void type.

c

Main

copy

              
12345678910111213

            
#include <stdio.h>

void func()
{
    printf("This function returns nothing\n");
}

int main()
{
    func();

    return 0;
}

The void keyword specifies that a function doesn't return a value, and it can also be used in the context of pointers. Attempting to declare a variable of type void will result in an error because the compiler won't understand how much memory to allocate.

Here's an intentional error for illustration.

c

Main

copy

              
12345678

            
#include <stdio.h>

int main()
{
    void variable;

    return 0;
}

Delving into Recursion

C supports the ability for a function to call itself, a technique known as recursion.

Imagine recursion as the action of stretching and then releasing a rubber band. It's commonly leveraged in mathematical operations, such as calculating factorials.

For instance: 3! = 3 x 2 x 1

Factorials are often utilized in approximating function values by expanding these functions into Taylor or Maclaurin series.

Note

This chapter's inspiration came right after the author completed a lab assignment at a university. The task was to approximate the cotangent value to a certain precision by expanding it into a Taylor series. And naturally, the factorial computation was indispensable.

c

Main

copy

              
1234567891011121314151617181920

            
#include <stdio.h>

int factorial(int n) 
{
    // if n = 0 or 1, because 0! = 1 and 1! = 1
    if (n == 0 || n == 1)
        return 1;
    // recursion case
    else
        return n * factorial(n - 1);
}

int main()
{
    int n = 3;

    printf("factorial(%d) = %d\n", n, factorial(n));

    return 0;
}

In the context of recursion, the function will continue to call itself until it meets the condition n == 0 || n == 1. Once this condition is satisfied, the results from the subsequent factorial() function calls are returned in the reverse order, similar to folding an accordion. By the time step 6 is reached, the initial call to factorial(3) will return 6.

question mark

Imagine an ad where you see a girl holding a bottle of milk. On this bottle, there's another picture of the same girl holding a bottle of milk, and on that smaller bottle, there's yet another picture of the girl, and so on. What's this concept called?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 5. ChapterΒ 6
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