20130413

How to use malloc for 2d array dynamic memory allocation


/*How to use malloc for 2d array dynamic memory allocation. How to write 2-d array with dynamic memory allocation */
#include<stdio.h>
#include<malloc.h>
int main()
{
int r,c,i,j;
printf("Enter No of rows and columns:");
scanf("%d%d",&r,&c);

int **array;
array=(int**)malloc(r*sizeof(int));

for(i=0;i<r;i++)
{
array[i]=malloc(c*sizeof(int));
}

How to use new to allocate memory for 3d array in CPP C++


/*How to use new to allocate memory for 3d array. How to use malloc for 3 dimensional array. CPP program for dynamically allocating memory for 3d array. How to write three dimensional array with malloc with new */

#include<iostream>
using namespace std;
int main()
{
// 3 Dimensions Array
// two 3x4 array
int x = 2, y = 3, z = 4;

int i, j, k;
// memory allocation for 3D

int ***array3D = new int**[x];
for(i = 0; i < x; i++)
{
array3D[i] = new int*[y];
for(j = 0; j < y; j++)
{
array3D[i][j] = new int[z];
}
}

20130411

How to learn stack and flow of function call and control in cpp

/*How to learn stack. Stack is memory in which Last in first out is followed.
When function call is encountered the address of the next statement is stored or pushed in the stack. When the control returns back from the definition to calling function the address is poped out which is nothing but the statement next to the function call and executed.*/
#include<stdio.h>
#include<iostream>
using namespace std;
void function1();
void function2();

int main()
{
printf("1\n");
printf("2\n");
function1();
printf("3\n");
printf("4\n");

return 0;
}
void function1()
{
printf("1.1\n");
printf("1.2\n");
function2();
printf("1.3\n");
printf("1.4\n");
}
void function2()
{
printf("2.1\n");
printf("2.2\n");
}

How to learn recursive function call in cpp/C++/C

/*How to learn recursive function call in cpp/C++/C
 Cpp Program to learn recursive function */
#include<iostream>
using namespace std;
int sum(int m, int k);
int main()
{
int i,m,k;
m=3;
k=2;
i=sum(m,k);
cout<<"sum="<<i<<endl;
//return 0;
}
int sum(int rm, int rk)
{
cout<<rm<<" "<<rk<<endl;
if(rm==0) return(rk);//termination condition
else return(1+sum(rk, rm-1));//recursive condition//if not +1 then sum=0
}

How to distinguish between call by value, call by reference, call by address

/*How to distinguish between call by value, call by reference, call by address.
Program to distinguish between pass by value,pass by reference,pass by address. Call by reference and call by address affects the calling value while call by value doe not. Most important difference is that in call by value new object is created which is some times such as when size of the variable is too large is not desirable so call by reference is preferred over call by value*/

#include<stdio.h>
#include<iostream>
using namespace std;
void callbyreference(int * x);//pass by address
int main()
{
int x;
x=10;
printf("Before x=%d",x);//10
callbyvalue(&x);
printf("\nAfter x=%d",x);//15
printf("\n");
return 0;
}

void callbyreference(int * x)
{
*x=*x+5;//mind the*
}


//CALL BY REFERNCE, PASS BY REFERNCE
/*