Main.cpp

 #include <iostream>
using namespace std;

main() 
  struct foo_t {
    int x[100];
    int var1;
    int y[10];
    } foo;
  int var2;
  long i;
  int *p, *q;
  short int *s;
  long int *l; 
  struct foo_t bar[50];

  for (i=0; i<100; i++) foo.x[i]=500+i;
  for (i=0; i<10; i++)  foo.y[i]=700+i;
  foo.var1 = 640;

  cout << sizeof(*s) << "\n";
  cout << sizeof(*p) << "\n";
  cout << sizeof(*l) << "\n";
  q = (int *) &foo;    cout << q << "\n";
  p=&(foo.x[5]);       cout << *p << "\n";
  // POINT 1
  q = (int *) &var2;   cout << q << "\n";
  q = p+16;            cout << *q << "\n";
  i = ((long) p) + 16;
  q = (int *) i;       cout << *q << "\n";
  s = (short *) i;     cout << *s << "\n";
  l = (long *) i;      cout << *l << "\n";
  q = p+95;            cout << *q << "\n";  // EXPLAIN
  q = p+98;            cout << *q << "\n";
  i = ((long) p) + 17;
  q = (int *) i;       cout << *q << "\n";
  q = p + _______;     cout << *q << "\n";
  q = (int *) (((long) p) + ______);  cout << *q << "\n";
  p = (int *) bar;
  *(p + _______) = 847; cout << bar[8].var1 << "\n";

created 2 years ago

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
}