//Write a C++ program to display factors of a number.


#include <iostream>
using namespace std;
int main() {
int n, i;
cout << "Enter a positive integer: ";
cin >> n;
cout << "Factors of " << n << " are: ";
for (i = 1; i <= n; ++i) {
if (n % i == 0) {
cout << i << " "; } } return 0; }


//Write a C++ program to create a text file which stores employee information as emp_id, emp_name, emp_sal). Write a menu driven program with the options a. Append b. 

//Modify c. Display d. Exit


#include <iostream>
#include <fstream>
#include <string>
using namespace std;
class Employee {
public:
 int emp_id;
 string emp_name;
 float emp_sal;
 
 void display() {
 cout << "ID: " << emp_id << ", Name: " << emp_name << ", Salary: " << emp_sal << endl;
 }
};
Employee readEmployee() {
 Employee emp;
 cout << "Enter employee ID: ";
 cin >> emp.emp_id;
 cout << "Enter employee name: ";
 cin.ignore();
 getline(cin, emp.emp_name);
 cout << "Enter employee salary: ";
 cin >> emp.emp_sal;
 return emp;
}
void appendToFile(string filename, Employee emp) {
 ofstream file;
 file.open(filename, ios::app);
 file << emp.emp_id << "," << emp.emp_name << "," << emp.emp_sal << endl;
 file.close();
 cout << "Employee added successfully.\n";
}
void modifyFile(string filename, int emp_id) {
 fstream file;
 file.open(filename, ios::in | ios::out);

 bool found = false;

 int pos;
 Employee emp;
 while (file >> emp.emp_id >> emp.emp_name >> emp.emp_sal) {
 if (emp.emp_id == emp_id) {
 found = true;
 pos = file.tellg() - sizeof(emp); 
 break;
 }
 }
 if (found) {
 emp = readEmployee();
 file.seekp(pos); 
 file << emp.emp_id << "," << emp.emp_name << "," << emp.emp_sal << endl;
 cout << "Employee modified successfully.\n";
 } else {
 cout << "Employee not found.\n";
 }
 file.close();
}
void displayFile(string filename) {
 ifstream file;
 file.open(filename);
 Employee emp;
 while (file >> emp.emp_id >> emp.emp_name >> emp.emp_sal) {
 emp.display();
 }
 file.close();
}
int main() {
 string filename = "employees.txt";
 int choice, emp_id;
 while (true) {
 cout << "Select an option:\n1. Append employee\n2. Modify employee\n3. Display all employees\n4. Exit\n";
 cin >> choice;
 switch (choice) {
 case 1:
 appendToFile(filename, readEmployee());
 break;
 case 2:
 cout << "Enter the employee ID to modify: ";
 cin >> emp_id;
 modifyFile(filename, emp_id);
 break;
 case 3:
 displayFile(filename);
 break;
 case 4:
 return 0;
 default:
 cout << "Invalid choice.\n";
 }
 }
 return 0;
}

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#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
}