C Programming Tutorial # 33 - malloc() and free() - Dynamic Memory Allocation - Part 1 [HD]

In this tutorial we learn about dynamic memory allocation using malloc(). We also learn about freeing up the dynamically allocated memory. We also see why it is not a good idea to create long local variables since they are created on stack.

This tutorial is part of the following series:

[thinkpad]

There are advantages and disadvantages of C versus C++ or any other programming language, and I won't claim that C is a "better" programming language than C++ (though there are many who would, and those who would claim the opposite), but it's certainly not obsolete. Its simplicity, ubiquity, efficiency and access to low-level functions make it very useful. And if nothing else C is still #1 on the TIOBE index meaning that it's the #1 most-used programming language in the world.

[Learnorama]

@itsdannyftw Yes, you can use malloc to allocate any number of bytes. Just specify the number. And this number can be input from the user, or it could be the length of a string, whatever.

[junior]

Am I the only one that get excited as his voice gets louder?

[DJTrancenergy]

I'm not a professional software engineer, I'm still student. But for the limited stuff I know, I've been told that much of the core and native stuff of operating systems is written C as it is faster.

[willuk]

@pithikoulis The newest C standard allows this, I believe; arrays on the stack without a constant length used to be illegal and so many people heard it and think it's wrong

[farmdve]

Thank you for the tutorial. I was wondering what is this stack and why would i need to ever use malloc.

[RandomGameHall]

good tutorial. i was worried because they complain about part 1 not being here.

[pithikoulis]

@amino0o is there an explanation to why this is illegal? i thought it was possible until you said the opposite. I don't know much C but in other languages I tryied it was possible to do what you mentioned.

[Learnorama]

Well, there may be a slight difference in speed between C code, and C++, the advantages that come with using C++ out-weight that slight difference. C++ is way more powerful than C to develop complex systems relatively quickly. It is much more modular and hence easy to maintain as well. All the cool things that come with using Object Oriented paradigm apply here.

[abdotassi]

when i do it in dev-c++ the compiler declare an error (invalid conversion ffrom ' void*' to 'int*'
please can you help me

[thatbennyguy]

His voice gets increasingly loud xD

Very good tutorial btw, for learning malloc(), free() etc.

[joshuademoraes]

how can I buid an array of chars like that: map [3000][3000] with 3000 rows and 3000 columns?
thx...

[hunchbacked]

C++ is not hardware, C++ is software.
I can understand that some operating systems can be written in C instead of C++, but common users don't write operating systems.
And C++ compilers can also compile ordinary C programs; the converse is not true.

[obzajd]

what's the name of the compiler you're using sir?

[Learnorama]

you will be surprised how much C is still used.

[Learnorama]

you are talking about embedded programming. Sure C++ can be used for embedded programming. I do it every day :-).

[kanrup]

nice explanation. not sure if I caught how to use free function.

[Lundburgerr]

Well, in order to burn the software into a PIC you need to compile your code into .hex files. Which as far as I know cannot be done for C++ programs.
But it can be done for C, hence the compiler issue.
Although I very much prefer the OO way of programming. C still has it's advantages over C++ in some circumstances.

[CripplingDuality]

@lepeanut

What's your point? It's still an industry standard.

[Learnorama]

Not in C. new can be used in C++, not in C. For C we are stuck with malloc :-) Dont forget to visit CPlusPlusTutor. com