raven radishBOT
tame whale
lets say you write a function to "make a new account" and call it 2 times , the variables inside of the function are created 2 times and destroyed 2 times ( assuming you make simple non static variables)
malloc is for allocating memory on the heap . So if you want to store some data on the heap , you will need to use malloc. You would store data on the heap when you dont know the size of it at compile time. or you want to be able to resize things etc
leaden viper
it is malloc. the way it works is that you request some more memory and malloc returns a pointer to it
tame whale
;compile
#include <stdio.h>
void foo(int a){
int x = a*2;
printf("The double of %d is %d\n", a,x);
}
int main()
{
foo(1);
foo(2);
}
boreal zenithBOT
tame whale
notice how in first case the value of x was 2 but in the next case it was 4
you dont have to "make new variables" to do that
now imagine instead of passing in int a , i pass in a string with the player's name. Then it can run the code and save that player's name to database
we never use malloc here
lilac matrix
can i post my code?
tame whale
yes , its best if you post the code and explain what u dont understand
leaden viper
it is malloc. the way it works is that you request some more memory and malloc r...
first you must specify the size of the data you want to create. for an integer you can use sizeof keyword to get its size and then pass it to malloc. then you can use the pointer that malloc returns like any normal pointer in C. lastly you'll need to free that allocated memory or you'll ran out of memory.
#include <stdio.h>
#include <stdlib.h>
int main() {
int *x = malloc(sizeof(int));
free(x);
}
int i;
int i2;
int i3;
int i6;
int inta;
scanf("%d", &inta);
int i4[inta][inta][inta][inta];
for (i = 0; i < inta; i++) {
for (i2 = 0; i2 < inta; i2++) {
for (i3 = 0; i3 < inta; i3++) {
for (i6 = 0; i6 < inta; i6++) {
i4[i][i2][i3][i6] = i + 1;
printf("[%d][%d][%d][%d][%d] ", i, i2, i3, i6, i4[i][i2][i3][i6]);
}
printf("\n");
}
printf("\n");
}
printf("\n");
}
So, this is the var: i4[i][i2][i3][i6]
I want to make an individual amount of variables(not array) and set them to any amount of 'scanf("%d",&inta);' that is imputed
WaterSerpentM
Formatted by Jarvis, Herald of Stark Tech
tame whale
so, from i4[i][i2][i3][i6] to individual ints
#include<stdio.h>
int main()
{
constexpr int length = 5;
int arr[length] = {};
for(int i=0; i<length; i++)
{
printf("Enter %dth int : \n", i);
scanf("%d",&arr[i]);
}
for(int i=0; i<length; i++)
{
printf("%dth number = %d\n",i ,arr[i] );
}
}
i think this is what u want ?
basically if you want to store 10 ints , instead of making 10 individual variables, you make an int array of lenght 10
so you can store 10 ints under 1 name
btw if u dont understand
constexpr int length = 5;
just assume its like (in reality , its really not, but u can assume they will do the same thing for now )
#define length 5
violet rock
note that this is C23 and will not be accepted by some compilers and might not be recognized as valid C by some instructors
tame whale
note that this is C23 and will not be accepted by some compilers and might not b...
the constexpr part ?
violet rock
constexpr, = {}
tame whale
={} is C23 ? damm
violet rock
there's = {0};
which is the common way of zeroing
lilac matrix
can it be this amount of length
( inta * inta * inta * inta)
tame whale
sure , but that looks like a pretty big number
so if inta is like 4 , you are making an array of length 256
can you explain what you are trying to do ?
lilac matrix
ye because i want to fill the array to the length
tame whale
ye because i want to fill the array to the length
not sure what u mean by that
violet rock
oh and also allocating a huge number of ints on stack (inside main fn) will cause a stack overflow
you either do malloc or static array
tame whale
yeah , if its a HUGE array or if you dont know the size of this array at compile time , you can allocate it on heap at runtime
lilac matrix
not sure what u mean by that
i4[i][i2][i3][i6] to malloc length ( inta * inta * inta * inta)
violet rock
it doesn't have to be that huge really.
1 mb is enough to stack overflow. and note that you won't be notified that you got a stack overflow. your program will run in a random way
tame whale
i4[i][i2][i3][i6] to malloc length ( inta * inta * inta * inta)
i4[i][i2][i3][i6] is a 4 dimensional array , you realise that right ?
lilac matrix
yes
violet rock
basically you need to do malloc
tame whale
can you give an example with numbers ?
also its very rare to see a 4 dimensional array , at least its my first time seeing it
lilac matrix
ye was just messing about
urban oak
you could just do a function translating 4d array to 1d array
lilac matrix
so, if ``` scanf("%d",&inta);
int i4[inta][inta][inta][inta];```
inta is inputed as 2,
then int i4 multiplies to 16 variables
raven radishBOT
@lilac matrix
lilac matrix
you could just do a function translating 4d array to 1d array
how do i do that
tame whale
if you want to allocate a 4 dimensional array on the heap of i4[i][i2][i3][i6] these dimensions , the process... is a bit involved
you first allocate an array of size i , and each element of this array is a pointer to pointer to pointer to int int ***
then you loop through each of these and then allocate an array of size i2 , each element of this array is int **
then you loop through each of these and then allocate an array of size i3, each element of this array is int*
then you loop through each of these and then finally allocate an array of size i6 , each element of this array is int
tame whale
you could just do a function translating 4d array to 1d array
this is probably the more sane choice
allocate a big 1D array of i * i2 * i3 * i6 and then make an interface to view it as a 4D array
urban oak
how do i do that
translate(i, i2, i3, i6) to i4[ i + i2* length + i3* length* length + i6* length* length*length]
lilac matrix
i did mention for it not to be an array, my project is for it to be individuel INT not array
tame whale
int array is just a container to store lot of ints
instead of making 216 individual variable names ,you can just make 1 variable and store all ints in it
lilac matrix
bit of a problem
int *mmm = malloc(inta*inta*inta*inta(int))```@lilac matrix
lilac matrix
any help?
int number[inta*inta*inta*inta] = {0};
int *mmm = malloc(inta*inta*inta*inta(int));```int number[intaintaintainta] = {0};
int mmm = malloc((intaintainta*inta) * sizeof(int));