//add rows
    for(i=0;i<3;i++)
    {
        sum=0;
    	for(j=0;j<3;j++)
    	{
    		sum+=a[i][j];
    	}
    	cout<<endl<<i+1<<" row sum = "<<sum;
    	

 //add columns
    for(i=0;i<3;i++)
    {
        sum=0;
    	for(j=0;j<3;j++)
    	{
    		sum+=a[j][i];
    	}
    	cout<<endl<<i+1<<" col sum = "<<sum;
    }

//add all elements
    for(i=0;i<3;i++)
    {
    	for(j=0;j<3;j++)
    	{
    		sum+=a[j][i];
    	}
    	
    }
    cout<<endl<<"All elements"<<sum;

Code :

// Online C++ compiler to run C++ program online
#include <iostream>
using namespace std;
int main() {
    int i=0,j=0,sum=0;
	int a[3][3];
	//input
    for(i=0;i<3;i++)
    {
    	for(j=0;j<3;j++)
    	{
    		cin>>a[i][j];
    	}
    }
    
    //add rows
    for(i=0;i<3;i++)
    {
        sum=0;
    	for(j=0;j<3;j++)
    	{
    		sum+=a[i][j];
    	}
    	cout<<endl<<i+1<<" row sum = "<<sum;
    	
    }
    cout<<"\\n------------------";
    //add columns
    for(i=0;i<3;i++)
    {
        sum=0;
    	for(j=0;j<3;j++)
    	{
    		sum+=a[j][i];
    	}
    	cout<<endl<<i+1<<" col sum = "<<sum;
    }
    cout<<"\\n------------------";
    //add all elements
    for(i=0;i<3;i++)
    {
    	for(j=0;j<3;j++)
    	{
    		sum+=a[j][i];
    	}
    	
    }
    cout<<endl<<"All elements"<<sum;
    

}

Stack:

// Online C++ compiler to run C++ program online
#include <iostream>
using namespace std;
struct stack{
    int stk[5];
    int top=-1;
}s1;

int overflow(){
    if(s1.top==4){
        cout<<"Stack Overflow";
        return 1;
    }
    else
    return 0;
}

int underflow(){
    if(s1.top==-1){
        cout<<"Stack Underflow";
        return 1;
    }
    else
    return 0;
}

void push(int val){
    if(overflow()){
        return;
    }
    else{
        s1.top++;
        s1.stk[s1.top]=val;
    }
}

void pop(){
    int val;
    if(underflow()){
        return;
    }
    else{
        val=s1.stk[s1.top];
        s1.top--;
        cout<<"Value deleted is "<<val;
    }
}

void peek(){
    cout<<s1.stk[s1.top];
}

int main() {
    int i,val,ch;
    while(i=1){
        cout<< "\\n\\nEnter the choice: "<<endl;
        cout<< "1. to push"<<endl;
        cout<< "2. to pop"<<endl;
        cout<< "3. to peek"<<endl;
        cout<< "0. to end"<<endl;
        cin>>ch;
        
        switch(ch)
        {
            case 1:
                int num;
                cout<<"Enter num : ";
                cin>>num;
                push(num);
                break;
                
            case 2:
                pop();
                break;
            case 3:
                peek();
                break;
            case 0:
                i=0;
                break;
            default:
                cout<<"Enter Valid option";
                break;
            
        }
    
    }
    return 0;
}