c++ array

i was trying to declare an array first then push value like these

#include<iostream>
using namespace std;

int main()
{
    unsigned var[];
    
    var[0] = 56;
    var[1] = 569;
    var[2] = 2;
    
}

Code (markup):

why its not working??

 

You need to specify array length:unsigned int var[3];or allocate memory for it runtime

 

tnx
but Array length is unknown
i mean in this example i used only 3 but in real script it cud be more or less..
allocate memory for it runtime
whts tht? how can u do tht? any example?
sorry im novice at c++

 

Ok

int main()
{
  int *var; //pointer to int

  int array_length = 3; //array length. this variable can be calculated

  var = new int(array_length); //allocate memory to array according array_length

  var[0] = 56;
  var[1] = 569;
  var[2] = 2;

}

Code (markup):

 

tnx again mate but still error wht im trying to do
here is my code

#include <iostream>

using namespace std ;

int main()
{
    int first;
    int second;
    int n=1;
    
    //maybe i hav to declare array variable here
    int allFirst;
    int allSeconds;
    
    do
    {
          cout << "enter first number: ";
          cin >> first;
          allFirst[n] = first;
          
          cout << "enter second number: ";
          cin >> second;
          allSecond[n] = second;

          n++;
              
    }while(first > second);
}

Code (markup):

so, its unknown how many loops...so whts arrays lengths. its varies
i hav to store all the inputs using Array. cant use another method
& although in example i used only int, i might have to add char, unsigned etc also

plz help (

 

Ushould use dynamic memory allocation. small example in c
int *ptr,len;

printf("Enter the size of array u want\n");
scanf("%d",&len);

ptr = malloc(len*sizeof(int));

then u can access ptr i starting from 0 to len .... This is simple c program buddy

 

You need to specify the length first.

 

Please use this one

unsigned var[] = {1, 2, 3};

 

void mail()
{
int * var;
var= new var[3];
var[0]=343;
var[1]=32;
varp2]=43;

}