Code keeps crashing exe (again)

[slender ivy]

#include <stdio.h>
#include <string.h>
#include <ctype.h>
int Prev_Room, quest_end;
char choice1;
int inputtest(char test1[], char test2[]);
void quest();
void room2();

int inputtest(char test1[], char test2[]) {
    size_t test1lenght = strlen(test1);
    int check1 = 0, check2 = 0;
    for (int i = 0; i < test1lenght; i++)
    {
        if ((test2[0] == test1[i]) && (test2[1] == test1[i+1])) {
            check1 = 1;
        }
    }
    return (check1 == 1)? 1:0;
    
}

void room1() {
    int leave_room1;
    leave_room1 = 0;
    while (leave_room1 != 1) {
        printf("Your are in room 1\n[1]: Quest\n[2]: Room 2\n");
        gets(choice1);
        if (inputtest(choice1, "qu") == 1) {
            system("cls");
            quest();
        }
        else if (inputtest(choice1, "ro") == 1) {
            system("cls");
            room2();
        }
    }
}

void quest() {
    printf("Type 1 to end quest\n");
    scanf("%d", &quest_end);
    if (quest_end == 1)
    {
        system("cls");
        room1();
    }
    
}

void room2() {
    int leave_room2;
    leave_room2 = 0;
    choice1 = 0;
    while (leave_room2 != 1) {
        printf("Your are in room 2\n[1]: Room 1\n");
        scanf("%d", &choice1);
        switch (choice1)
        {
        case 1:
            system("cls");
            room1();
        }
    }
}



int main() {
    system("cls");
    room1();
    return 0;
}

[thorny python]

When your question is answered use !solved to mark the question as resolved.

Remember to ask specific questions, provide necessary details, and reduce your question to its simplest form. For tips on how to ask a good question use !howto ask.

[glad inlet]

choice1 is a char, which can only store a single letter. A string is an array of chars

Also, gets is unsafe and deprecated. use fgets instead

[slender ivy]

What’s the difference between gets and fgets

[glad inlet]

fgets takes the length of the buffer it's reading into, so it can stop and avoid a buffer overflow

[thorny python]

cppreference.com

fgets

char* fgets(char* str, int count, FILE* stream);
// ... and 1 more

Defined in

<stdio.h>

[slender ivy]

What’s a buffer overflow

What’s a buffer

[signal flicker]

Excerpt from the fgets manpage:

Bugs
Never use gets(). Because it is impossible to tell without knowing the data in advance how many characters gets() will read, and because gets() will continue to store characters past the end of the buffer, it is extremely dangerous to use. It has been used to break computer security. Use fgets() instead.

[signal flicker]

A buffer is just some memory, like e.g. char my_buffer[100]; <-- this would be a 100 byte buffer

[glad inlet]

char str[5]; // only has 5 spaces
for (int i = 0; i < 10; i++) {
  str[i] = 'a'; // this will keep going past the last space and write into whatever memory is after the array
}

[slender ivy]

100 bytes???? Not bits???

[glad inlet]

C only counts sizes in bytes, we don't have direct interaction with bits (outside of bitwise integer operations)

[slender ivy]

Ah I see, that sounds like it would fuck up a code

[signal flicker]

We have 100 chars.
1 char is 1 byte.

[signal flicker]

(or bitfields)

[slender ivy]

Damn… arrays will kill my memory won’t they

[signal flicker]

no, haha

[glad inlet]

why would they

[signal flicker]

Smth like

char buf[1'000'000];
```would be 1 megabyte (1 MB)

[slender ivy]

1 infinte loop combined with an array and its GGs

[signal flicker]

char buf[1'000'000'000]; would be 1 GB (although that'd be too large for your stack)

[signal flicker]

No?

Arrays aren't created at runtime

[glad inlet]

that only matters if you end up computing a bad index to access the array with

[slender ivy]

Whats a stack

[slender ivy]

Oh right mb

[glad inlet]

char arr[2];
while (1) {
  arr[0] = 'a'; // infinite loop but no issues
}

[slender ivy]

Yeah I see why I sounded dumb

[signal flicker]

Just a part of your program's memory space

[slender ivy]

I see, how big is the stack? And do I ever have to worry about the issue of it being too full?

[signal flicker]

no issues besides your CPU core responsible for that program "idling" at 100% usage

[glad inlet]

depends on the system, but usually a couple megabytes on modern desktop computers

[signal flicker]

If you want more memory then you'll need to use the heap where you can get memory from using malloc

!man malloc

[thorny python]

man7

malloc(3)

malloc, free, calloc, realloc, reallocarray - allocate and free dynamic memory

Synopsis

#include <stdlib.h>

void *malloc(size_t size);
void free(void *ptr);
void *calloc(size_t nmemb, size_t size);
void *realloc(void *ptr, size_t size);
void *reallocarray(void *ptr, size_t nmemb, size_t size);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

reallocarray():
    Since glibc 2.29:
        _DEFAULT_SOURCE

... (truncated)

[signal flicker]

Big advantage of malloc is not only that you have practically unlimited memory but also that you can allocate that memory at runtime e.g. from a user input

[slender ivy]

Unlimited sounds like it wouldn’t end well for me ngl

[signal flicker]

Disadvantage is that you need to manually free it and that it's a bit slower than the stack

[glad inlet]

heap isn't slower than stack

heap allocations are slower than stack allocations

access is same

[signal flicker]

Well, it's not really unlimited. Can only go up to how much RAM you have (+ a bit more due to operating system magic)

[signal flicker]

Yeah, I didn't want to dive too deep for now

But yeah, the whole OS part around it is what makes it slow

[slender ivy]

Man, okay time to get a degree in CS ig, screw engineering

[glad inlet]

engineering is cooler

[swift lagoon]

id say memory management is more computer engineering than CS

CS is mainly algorithms, graph and set theory, linear algebra and stuff

probability

[slender ivy]

Okay then, time to switch majors, screw mechatronics

[swift lagoon]

"Computer science" is kind of a bad wording, its more "Computing science"

[glad inlet]

mechatronics is dope tho

[slender ivy]

(It is, but we just don’t get deep enough into anything)

[glad inlet]

well yeah, undergrad

join an engineering club and write code for them

[swift lagoon]

well you cant really fill your memory with general data if you arent working with huge arrays

[signal flicker]

Insert childish "that's what she said" joke

[slender ivy]

Do u think there are online clubs I can join

[swift lagoon]

like i made a small 2d game in C for last semesters homework assignment(2k lines of code, not too much), it uses like 30 MBs of memory with all textures and text loaded into memory after they are used once

[slender ivy]

My uni don’t got engineering clubs, mostly community

[slender ivy]

YO WAI- THERES A GUI IN C?

[glad inlet]

not built-in

[swift lagoon]

I used a library :)

[slender ivy]

Which one?

[swift lagoon]

https://www.libsdl.org/

always my go-to for simple stuff

[slender ivy]

Is it hard to use?

I’m currently attempting to make a game for my final project in C

[glad inlet]

start one. the club I joined was started when some students were digging around in the engineering building's basement, found some cool stuff, and decided to make stuff with it

[slender ivy]

Oh I don’t have enough knowledge in anything in engineering to start a whole as club, I can barely write some code and I suck ass at mechanics

[glad inlet]

there's only one way to learn

those students didn't know squat about the things they found

found a professor who did to advise them, learned the rest as they went

knowledge gets passed down each year, and while I was there we ended up setting a couple world records

[slender ivy]

I’m planning to go to a course this summer that dives deep into all engineering aspects, they told me that at the end of the course I’ll have to submit a project that’s on the level of an engineering graduation project

[slender ivy]

Would that’s badass

[swift lagoon]

not really.

https://github.com/nevemlaci/Prog1_NHF1 this is the whole project

i think you can just

git clone https://github.com/nevemlaci/Prog1_NHF1.git

and open it up with visual studio code and run it with the play button at the top right(i have a visual studio code task attached for running/debugging)

the code is horrible tho

but basically sdl allows you to create a window, renderer and load+render textures and stuff

very basic media library

[slender ivy]

I see, ill do that when i get the internet to downlaod things 👍

[signal flicker]

You only got the upload version of the internet rn?

[slender ivy]

(Internet is going at 2b/s on my laptop rn)

[signal flicker]

Huh? How can you even send and receive Discord texts

[glad inlet]

easily, I'm working on a 22b/s connection right now

[slender ivy]

It takes a sec, but i send most of the messages on phone

Which is running on data

[signal flicker]

Isn't that like ~60-100 characters per second?
So if I send an incredibly long paragraph of say 2k characters that all require 4 bytes UTF-8, then it'd take you more than a minute to receive the whole text, no?

[glad inlet]

yeah

it's one packet per 5.6 seconds

[signal flicker]

x)

ouch

[glad inlet]

128 bits of data per packet

low-power satellite link

[signal flicker]

why?

[glad inlet]

more speed = more power

[signal flicker]

I mean you could almost carry the data by hand to Discord and it'd be faster

[glad inlet]

https://en.wikipedia.org/wiki/IP_over_Avian_Carriers

[signal flicker]

Is there also such a joke article for "IP over Aryan Carriers"?

[glad inlet]

not that I know of

but there's HTCPCP

[signal flicker]

Hyper Text Coffee Pot Control Protocol

nice

[glad inlet]

https://www.rfc-editor.org/rfc/rfc2324

IETF has good april fools

[signal flicker]

@glad inlet Such a shame that you don't know German, because there's an entirely different Wikipedia dedicated to joke articles, like e.g. the "W-Lan-cable" or the "W-Lan-pipe".

E.g. for the "W-Lan-cable" they even give the materials it's build from:

• 78.1% Nitrogen
• 20.9% oxygen
• 0.93% Argon
• 0.03% carbon dioxide
• 0.01% hydrogen
• 10.98% plutonium
• 2.718% Dilithium
• 1.93% oxdrahdium
• 0.002% anionic and non-ionic surfactants
• 0.001% pro-retinol-α nanosomes (prevent wrinkling)

[slender ivy]

It’s made of… earths atmosphere?

[glad inlet]

I really don't think that the earth's atmosphere is 10.98% plutonium

[signal flicker]

If this is a serious question then think about it again.
What does the W in W-Lan stnad for?

Yeah, up to the hydrogen it's the earth's atmosphere, starting from the plutonium we're actually surpassing the 100% barrier

[glad inlet]

the dilithium is important so we can maintain a warp field tho

[signal flicker]

true

wouldn't want to imagine what it'd be like without warping.

Imagine travelling by moving like a peasant

[glad inlet]

I prefer gate travel personally

[split nexus]

not yet…

[fallen nebula]

Silly, of course it is