- Why should we use functions ?
- What are examples of functions in real-world  ?
- How to declare and define functions ?
- Implemented Strlen function in C.

داخل این ویدیو درمورد فانکشن ها صحبت کردم.
چجوری فانکشن هارو تعریف کنیم. استفاده کنیم.
درمورد فانکشن ها داخل دنیای واقعی صحبت کردم.
فانکشن strlen رو خودمون نوشتیم که ببینیم چجوری داره کار میکنه
و چجوری یک فانکشن نوشته میشه و به کار میاد

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It had a Zilog Z-80 processor. With 1K of memory for the screen (character display) and another 1K for use by programs.
There was no room for a compiler or an assembler. So to create a program, you entered opcodes into the memory as hexadecimal numbers.
So, for example, if your program started with loading the A register with the number 3. - You might think of this as the assembly instruction:
LD A,3
But then you would need to look-up the opcode in a book (or memorise it). And type in
3E 03
I wrote a few programs on it. A version of Game of Life - And a simple side-scrolling shooter. (where the graphics were various alphabetic characters).
There was no bin file, or files of any kind, because there was no operating system to interpret such a file. There was the ability to dump a block of memory directly to a tape. And this is how programs were saved and loaded.

int i = 0;
while (arr[i] != '\0') {
    i++;
}
return i;

#define RET_OK 0
#define RET_NOK 1

int add (int a, int b) {
    return a + b;
}

int main() {
    int s = 43;

    int (*func_ptr)(int, int) = add;
    int res = func_ptr(s, ++s);
    printf("%i\n", res);
    return RET_OK;
}