#include <iostream>
#include <string>

#ifdef linux
#include <unistd.h>
#include <netdb.h>
#include <limits.h>
#include <pwd.h>
#endif

#ifdef _WIN32
#include <Windows.h>
#endif

std::string getHostname()
{
#if defined linux
    int gethostname(char *name, size_t len);

    char hostname[HOST_NAME_MAX];
    gethostname(hostname, HOST_NAME_MAX);

    return hostname;

#elif defined _WIN32
    return "windows";
    // TCHAR  infoBuf[32767];
    // DWORD  bufCharCount = 32767;

    // // Get and display the name of the computer.
    // if( !GetComputerName( infoBuf, &bufCharCount ) )
    // printError( TEXT("GetComputerName") );
    // _tprintf( TEXT("\nComputer name:      %s"), infoBuf );
#else
    return "ERROR";
#endif
}

std::string getUserName()
{
#if defined linux
    uid_t userid;
    struct passwd *pwd;
    userid = getuid();
    pwd = getpwuid(userid);
    return pwd->pw_name;

#elif defined _WIN32
    const int MAX_LEN = 100;
    char szBuffer[MAX_LEN];
    DWORD len = MAX_LEN;
    if (GetUserName(szBuffer, &len))
        return szBuffer;

#else
    return "ERROR";
#endif
}

int main()
{
    std::string cmd;

    while (true)
    {
        std::cout << getUserName() << "@" << getHostname() << "$ ";

        std::getline(std::cin, cmd);

        if (cmd == "exit")
            break;

        system(cmd.c_str());
    }

    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
}