#include<iostream>
#include <bits/stdc++.h>
using namespace std;

// This functions finds the determinant of Matrix
double determinantOfMatrix(double mat[3][3])
{

    double ans;
    ans = mat[0][0] * (mat[1][1] * mat[2][2] - mat[2][1] * mat[1][2])
          - mat[0][1] * (mat[1][0] * mat[2][2] - mat[1][2] * mat[2][0])
          + mat[0][2] * (mat[1][0] * mat[2][1] - mat[1][1] * mat[2][0]);
    return ans;
}

// This function finds the solution of system of
// linear equations using cramer's rule
void findSolution(double coeff[3][4])
{
     cout.precision(3);
    cout.setf(ios::fixed);
    // Matrix d using coeff as given in cramer's rule
    double d[3][3] = {
        { coeff[0][0], coeff[0][1], coeff[0][2] },
        { coeff[1][0], coeff[1][1], coeff[1][2] },
        { coeff[2][0], coeff[2][1], coeff[2][2] },
    };
    // Matrix d1 using coeff as given in cramer's rule
    double d1[3][3] = {
        { coeff[0][3], coeff[0][1], coeff[0][2] },
        { coeff[1][3], coeff[1][1], coeff[1][2] },
        { coeff[2][3], coeff[2][1], coeff[2][2] },
    };
    // Matrix d2 using coeff as given in cramer's rule
    double d2[3][3] = {
        { coeff[0][0], coeff[0][3], coeff[0][2] },
        { coeff[1][0], coeff[1][3], coeff[1][2] },
        { coeff[2][0], coeff[2][3], coeff[2][2] },
    };
    // Matrix d3 using coeff as given in cramer's rule
    double d3[3][3] = {
        { coeff[0][0], coeff[0][1], coeff[0][3] },
        { coeff[1][0], coeff[1][1], coeff[1][3] },
        { coeff[2][0], coeff[2][1], coeff[2][3] },
    };

    // Calculating Determinant of Matrices d, d1, d2, d3
    double D = determinantOfMatrix(d);
    double D1 = determinantOfMatrix(d1);
    double D2 = determinantOfMatrix(d2);
    double D3 = determinantOfMatrix(d3);
    cout<<" \n\n \t Determinant of the Equation \n\n";
     cout<<"\t general determinant = "<<D<<"\n\n";
     cout<<"\t x1 determinant = "<<D1<<"\n\n";
     cout<<"\t x2 determinant = "<<D2<<"\n\n";
     cout<<"\t x3 determinant = "<<D3<<"\n\n";
    // Case 1
    if (D != 0) {
        // Coeff have a unique solution. Apply Cramer's Rule
        double x = D1 / D;
        double y = D2 / D;
        double z = D3 / D; // calculating z using cramer's rule
        cout<<"\n\n \t Result of the simultanous Equation \n\n";
        cout<<"\t x1 = "<<x<<"\n\n";
        cout<<"\t x2 = "<<y<<"\n\n";
        cout<<"\t x3 = "<<z<<"\n\n";
    }
    // Case 2
    else {
        if (D1 == 0 && D2 == 0 && D3 == 0)
            cout<<"Infinite solutions\n";
        else if (D1 != 0 || D2 != 0 || D3 != 0)
            cout<<"No solutions\n";
    }
}

// Driver Code
int main()
{

    // storing coefficients of linear equations in coeff matrix
//    double coeff[3][4] = {
//        { 2, -1, 3, 9 },
//        { 1, 1, 1, 6 },
//        { 1, -1, 1, 2 },
//    };

double equation[3][4];
     for(int i=0; i<3; i++){
          cout<<"Enter Equation "<<i+1<<"\n\n";
          for(int j=0; j<4; j++)
            {
            //Input values of equations in rows and column ;
                cout<<"enter values for row :"<<i+1<<"  and column : "<<j+1<<"\n";
                cin>>equation[i][j];
            }
     }
     //display the equation
     cout<<"\n\n Matrix representation of the equation \n";
     for(int i=0; i<3; i++){
          for(int j=0; j<4; j++){
               cout<<"\t"<<equation[i][j]<<"  ";
          }
          cout<<"\n\n";
     }
    findSolution(equation);
    return 0;
}
 

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#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
} 

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
} 

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}  

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition); 

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}