calculator program in c++ using functions

Write a program for a simple c++ calculator which have different functions for different operations. Make a menu base selection screen using switch statement. Ever operation should have its own function. This code may also be use as a mini project to start. 
Calculator should have following operations.

• Addition
• Subtraction
• Multiplication
•  Division
• Square root
• Factorial
• Exponential 

This code has been tested on Code blocks c++ compiler

C++ Source Code:

#include<iostream>
#include<conio.h>
#include<math.h>
#include<stdlib.h>
#include<iomanip>
  char op;
using namespace std;
void sum()
   {
     
    int sum = 0;
    int n;
    int numberitems;
    cout << "Enter number of items: \n";
    cin >> numberitems;

    for(int i=0;i<numberitems;i++)
    {
        cout<< "Enter number "<<i<<":\n\n" ;
        cin>>n; 
        sum+=n;
    }
    cout<<"sum is: "<< sum<<endl<<endl;
    
    }
void diff()
    {
     int diff;
     int n1,n2;
     cout<<"enter two numbers to find their difference:\n\n";
     cout<<"enter first number:";
     cin>>n1;
     cout<<"\nenter second number:";
     cin>>n2;
     diff=n1-n2;
     cout<<"\ndifference is:"<<diff<<endl<<endl;
     }
     
void pro()
    
    {
     int pro=1;
     int n;
     int numberitems;
     cout<<"enter number of items:\n";
     cin>>numberitems;
     for(int i=0;i<=numberitems;i++)
     {
             cout<<"\nenter item "<<i<<":";
             cin>>n;
             pro*=n;
     }
             
     cout<<"product is:"<<pro<<endl<<endl;    
     }
       
 void div()
     {
      int div;
      int n1;
      int n2;
      cout<<"enter 2 numbers to find their quotient\n\n";
      cout<<"enter numerator:";
      cin>>n1;
      cout<<"\nenter denominator:";
      cin>>n2;
      div=n1/n2;
      cout<<"\nquotient is:"<<div<<endl<<endl;
      }      

void power()
     {     
     long int p;
     int res=1,n; 
     cout<<"enter number:";
     cin>>n;
     cout<<"\nenter power:";
     cin>>p;
     for(int i=1;i<=p;i++)
     {
      res=n*res;
     }
      cout<<n<<"\n power "<<p<<" is :"<<res<<endl;
     } 
       
void sq()
     {
     float s;
     int n;
     cout<<"enter number to find its square root:";
     cin>>n;
     s=sqrt(n);
     cout<<"\nsquare root of "<<n<<" is :"<<s<<endl;
     }
 void fact()
     {
      long int f=1;
      int c=1,n;
      cout<<"enter number to find its factorial:";
      cin>>n;
      while(c<=n)
      {
                 f=f*c;
                 c+=1;
      }     
                 cout<<"\nfactorial of "<<n<<" is :"<<f<<endl;     
      }
void expo()
     {
          long double res=1,p; 
     double e=2.718281828;     
     cout<<"enter power of exponential function:";
     cin>>p;
     for(int i=1;i<=p;i++)
     {
      res=e*res;
     }
      cout<<" e^ "<<p<<" is :"<<res<<endl;
           
           }
int main()
{   
    
    
    system("cls");
    do
    {
                
    system("pause");              
    system("cls");    
    cout<<"***which operation you want to perform***\n";
    cout<<"press 0 for exit\n";
    cout<<"press 1 for addition \n";
    cout<<"press 2 for subtraction\n";
    cout<<"press 3 for multiplication\n";
    cout<<"press 4 for division\n";
    cout<<"press 5 for power calculation\n";
    cout<<"press 6 for square root \n";
    cout<<"press 7 for factorial calculation\n";
    cout<<"press 8 for exponential calculation\n";
    cout<<"press option:";
    cin>>op;
    switch(op)
    {
              case '1':
              sum();
              
              break;
              case '2':
              diff();
              break;
              case '3':
              pro();
              break;
              case '4':
              div();
              break;
              case '5':
              power();
              break;
              case '6':
              sq();
              break;
              case '7':
              fact();
              break;
              case '8':
              expo();
              break;     
              case '0':
              exit(0);    
              default:
              cout<<"invalid input"  ;
              system("cls");
    } 
    }
                                                                         
    while(op!='0');
                    
                    getch();
                    }

Program output video

Image output

output on code blocks console

Find more examples here: C++ simple example source code and explanation with dry run

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student record c++ programming project for beginners

Project Introduction and scope
It is a simple c++ project for beginners to cover some basic topics. Which can help c++ beginners to build large projects and gives idea about how to make project in c++ programming. To keep the project simple only basic functionalities has added it is recommended for students first understand the project flow then add more functions like edit record (hint code also has given below) etc. Best practice for students is to first add validation in this project which will not allow user to enter wrong option and then add more functions.

It includes the concept of following topics

• struct 
• Filing 
• Loops
• Arrays
• If else
• Switch statement
• String class functions

Project has for major functions in menu

1. Insert record
2. Show all record
3. Search record
4. Exit program

How it works

Each  functionality has a function call in switch statement on the user choice control transfers to a function. Every function opens a file name "database" and insert, show and search data from it. File will be created where c++ file is placed in secondary storage.

C++ project source code

#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>
#include<fstream.h>

struct student
{
 char name[20];
 char reg[15];
 char course[10];
 float cgpa;
};

fstream file;
student obj;

void add()
{
 cout<<"Enter Name: ";
 cin>>obj.name;
 cout<<"Enter Registration Number: ";
 cin>>obj.reg;
 cout<<"Enter Course: ";
 cin>>obj.course;
 cout<<"Enter CGPA: ";
 cin>>obj.cgpa;

 file.open("database.txt",ios::app) ;
 file.write((char*)&obj,sizeof(obj));
 file.close();
}

void show_all()
{     //  clrscr();
 file.open("database.txt",ios::in);
 file.read((char*)&obj,sizeof(obj));

 while (file.eof()==0)
 {
  cout<<"Name: "<<obj.name<<endl;
  cout<<"Registration Number: "<<obj.reg<<endl;
  cout<<"Course: "<<obj.course<<endl;
  cout<<"CGPA: "<<obj.cgpa<<endl<<endl;

  file.read((char*)&obj,sizeof(obj));
 }
 file.close();

 getch();
}

void search()
{      // clrscr();
 float user;
 cout<<"Enter CGPA: ";
 cin>>user;
 file.open("database.txt",ios::in);
 file.read((char*)&obj,sizeof(obj));

 while (file.eof()==0)
 {
  if (obj.cgpa==user)
  {
   cout<<"Name: "<<obj.name<<endl;
   cout<<"Registration Number: "<<obj.reg<<endl;
   cout<<"Course: "<<obj.course<<endl;
   cout<<"CGPA: "<<obj.cgpa<<endl<<endl;
  }

  file.read((char*)&obj,sizeof(obj));
 }
 file.close();

 getch();
}

void edit()
{     //  clrscr();

 char user[15];
 cout<<"Enter registration Number: ";
 cin>>user;

 file.open("database.txt",ios::in|ios::out);
 file.read((char*)&obj,sizeof(obj));

 while (file.eof()==0)
 {
  if (strcmp(obj.reg,user)==0)
  {
   cout<<"Name: "<<obj.name<<endl;
   cout<<"Registration Number: "<<obj.reg<<endl;
   cout<<"Course: "<<obj.course<<endl;
   cout<<"CGPA: "<<obj.cgpa<<endl<<endl;

   cout<<"\nEnter New course: ";
   cin>>obj.course;

   file.seekp(file.tellg()-sizeof(obj));
   file.write((char*)&obj,sizeof(obj));
   cout<<"\n\nFile Updated";
   break;
  }

  file.read((char*)&obj,sizeof(obj));
 }
 file.close();

 getch();
}


void main()
{
// clrscr();

 //file.open("c:\database.txt",ios::out);
 //file.close();
 int option;

 while(1)
 {
 // clrscr();
  cout<<"Enter 1 to Enter Record\n";
  cout<<"Enter 2 to Show All Record\n";
  cout<<"Enter 3 to Search Record\n";
  cout<<"Enter 4 to Exit\n";
  cout<<"\n\nEnter Option: ";
  cin>>option;

  switch (option)
  {
   case 1:
    add();
    cout<<"\n\nRecord Entered\n";
    getch();
    break;
   case 2:
    show_all();
    break;
   case 3:
    search();
    break;
   case 4:
    exit(0);
  }
 }
 getch();
}

sample input output

Source code has been tested on Microsoft Visual C++ compiler. If you are running on a different compiler like codeBlocks. Some changes may required like add using namespace std; , remover .h from iostream etc.

Reference edit functionality c++ source code for practice

void edit()
{     //  clrscr();

 char user[15];
 cout<<"Enter registration Number: ";
 cin>>user;

 file.open("database.txt",ios::in|ios::out);
 file.read((char*)&obj,sizeof(obj));

 while (file.eof()==0)
 {
  if (strcmp(obj.reg,user)==0)
  {
   cout<<"Name: "<<obj.name<<endl;
   cout<<"Registration Number: "<<obj.reg<<endl;
   cout<<"Course: "<<obj.course<<endl;
   cout<<"CGPA: "<<obj.cgpa<<endl<<endl;

   cout<<"\nEnter New course: ";
   cin>>obj.course;

   file.seekp(file.tellg()-sizeof(obj));
   file.write((char*)&obj,sizeof(obj));
   cout<<"\n\nFile Updated";
   break;
  }

  file.read((char*)&obj,sizeof(obj));
 }
 file.close();

 getch();
}

Hope this code will help. Check also
School management c++ project source code. To check some example codes see more at  simple c++ code examples.

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