kindred pine
guys what is special about main() and how is it different from other functions
ive seen people put a lot of emphasis on the main function in cpp, however i cant tell how its different from other functions. im also not sure if functions in cpp have to be called like python so id like some clarity on that pls
boreal canyonBOT
chrome ridge
main is the default entry point of the program, meaning it starts there (besides initializing global variables which can involve functions).
kindred pine
ohhh
but ive seen people start with other functions
and other people writing other functions outside of the main function
chrome ridge
There is WinMain for Windows GUI subsystem something. That's pretty much it.
chrome ridge
No. Usually it's last.
tulip notch
I think they mean first to be executed?
kindred pine
but its the entry point?
kindred pine
I think they mean first to be executed?
well yeah, so other code can be executed after it
if its last then only main would be executed no?
or does cpp not work like that
tulip notch
OH I see
kindred pine
yeh xD
chrome ridge
When your program is
#include <iostream>
void f() {
std::cout << 1;
}
int main() {
std::cout << 2;
}
then 2 gets printed and 1 does not. That's what makes main special.
tulip notch
So ya, C is not like python
chrome ridge
(Also it has implicit return 0; and you are not allowed to call it)
kindred pine
When your program is
```cpp
#include <iostream>
void f() {
std::cout << 1;
}
...
but then f() is useless no?
in that cpde
chrome ridge
It mostly is. Someone else might do f(); though and then it has a use.
kindred pine
So ya, C is not like python
yess i think thats it xD but how?
chrome ridge
Sort of
kindred pine
It mostly is. Someone else might do `f();` though and then it has a use.
oh wow so the functions can be called like py
tulip notch
The top level is not executed. The only thing it does is define functions and variables.
In C, everything that is executed is in a function, so there has to be a fist function that gets called, and that is main
chrome ridge
Sure
kindred pine
but main gets automatically run
chrome ridge
Yup
tulip notch
Yep
chrome ridge
There are other functions that get automatically run. Like
int g() {
f();
return 42;
}
int i = g();
calls g and then f before main, so "main gets called first" is not quite correct.
tulip notch
Hold on a moment, I think I know a good example
kindred pine
so what if i do this
#include <iostream>
std::cin >> x;
int main(x) {
std::cout<< x + "\n" << endl;
}```this probably has errors in it but
tulip notch
You can't
kindred pine
oh dang
tulip notch
You can't execute statements outside of a function
kindred pine
wooah i see i see
lone fable
int i = printf("Hello World!");
int main(){}
is a classic
kindred pine
There are other functions that get automatically run. Like
```cpp
int g() {
f(...
thats so cool I see I see
it makes sense
kindred pine
```cpp
int i = printf("Hello World!");
int main(){}
```
is a classic
but i thought i cant execute statements before main function-
tulip notch
Okay to clarify
The only statement you can have outside a function is variable definitions
lone fable
Yes
chrome ridge
It's honestly a dumb restriction. Originally C did not allow such things and required main to actually be the first function to call. No trickery with initializing a variable with a function call either. C++ inherited that, but because of constructors had to relax the rules. Nowadays may as well allow top level statements and get rid of main.
lone fable
printf happens to return a number so it can be used to initialise global variables
kindred pine
printf happens to return a number so it can be used to initialise global variabl...
wait i just realized, the piece of code you sent started with int and returned a string, does it like return 1??
kindred pine
It's honestly a dumb restriction. Originally C did not allow such things and req...
Ah I see I see
boreal canyonBOT
chrome ridge
Return value
1,2) Number of characters written if successful or a negative value if an error occurred.
lone fable
printf returns a number and prints to the screen as a side effect
chrome ridge
strlen is dumb, just use printf :4head:
tulip notch
🤣
boreal canyonBOT
@kindred pine Has your question been resolved? If so, run !solved :)
boreal canyonBOT
kindred pine
!solved
kindred pine
nicee