Basic C++ Syntax Interview Preparation Guide

Download PDF

Strings are arrays of chars. String literals are words surrounded by double quotation marks.
"This is a static string"
To declare a string of 49 letters, you would want to say:
char string[50];

To access a variable of the structure it goes:

name_of_single_structure.name_of_variable;
For example:
struct example {
int x;
};
struct example an_example; //Treating it like a normal variable type
an_example.x = 33; //How to access its members

The format for defining a structure is:

struct Tag {
Members
};
Where Tag is the name of the entire type of structure and Members are the variables within the struct. To actually create a single structure the syntax is
struct Tag name_of_single_structure;

The general format for a prototype is simple:
return-type function_name ( arg_type arg1, ..., arg_type argN );
arg_type just means the type for each argument -- for instance, an int, a float, or a char. It's exactly the same thing as what you would put if you were declaring a variable.

The prototype for that function is:
istream& getline(char *buffer, int length, char terminal_char);
The char *buffer is a pointer to the first element of the character array, so that it can actually be used to access the array. The int length is simply how long the string to be input can be at its maximum (how big the array is). The char terminal_char means that the string will terminate if the user inputs whatever that character is. Keep in mind that it will discard whatever the terminal character is.

It is possible to make a function call of cin.getline(arry, 50); without the terminal character. Note that 'n' is the way of actually telling the compiler you mean a new line, i.e. someone hitting the enter key.

For a example:
#include <iostream>

using namespace std;

int main()
{
char string[256]; // A nice long string

cout<<"Please enter a long string: ";
cin.getline ( string, 256, 'n' ); // Input goes into string
cout<<"Your long string was: "<< string <<endl;
cin.get();
}</endl;
</iostream>

#include <iostream>

using namespace std;

void playgame()
{
cout << "Play game called";
}
void loadgame()
{
cout << "Load game called";
}
void playmultiplayer()
{
cout << "Play multiplayer game called";
}

int main()
{
int input;

cout<<"1. Play gamen";
cout<<"2. Load gamen";
cout<<"3. Play multiplayern";
cout<<"4. Exitn";
cout<<"Selection: ";
cin>> input;
switch ( input ) {
case 1: // Note the colon, not a semicolon
playgame();
break;
case 2: // Note the colon, not a semicolon
loadgame();
break;
case 3: // Note the colon, not a semicolon
playmultiplayer();
break;
case 4: // Note the colon, not a semicolon
cout<<"Thank you for playing!n";
break;
default: // Note the colon, not a semicolon
cout<<"Error, bad input, quittingn";
break;
}
cin.get();
}</iostream>

Switch case statements are a substitute for long if statements that compare a variable to several "integral" values ("integral" values are simply values that can be expressed as an integer, such as the value of a char). The basic format for using switch case is outlined below. The value of the variable given into switch is compared to the value following each of the cases, and when one value matches the value of the variable, the computer continues executing the program from that point.
switch ( <variable> ) {
case this-value:
Code to execute if <variable> == this-value
break;
case that-value:
Code to execute if <variable> == that-value
break;
...
default:
Code to execute if <variable> does not equal the value following any of the cases
break;
}</variable></variable></variable></variable>

When the programmer actually defines the function, it will begin with the prototype, minus the semi-colon. Then there should always be a block with the code that the function is to execute, just as you would write it for the main function. Any of the arguments passed to the function can be used as if they were declared in the block. Finally, end it all with a cherry and a closing brace. Okay, maybe not a cherry.
Let's look at an example program:
#include <iostream>

using namespace std;

int mult ( int x, int y );

int main()
{
int x;
int y;

cout<<"Please input two numbers to be multiplied: ";
cin>> x >> y;
cin.ignore();
cout<<"The product of your two numbers is "<< mult ( x, y ) <<"n";
cin.get();
}

int mult ( int x, int y )
{
return x * y;
}</iostream>

Functions that a programmer writes will generally require a prototype. Just like a blueprint, the prototype tells the compiler what the function will return, what the function will be called, as well as what arguments the function can be passed. When I say that the function returns a value, I mean that the function can be used in the same manner as a variable would be. For example, a variable can be set equal to a function that returns a value between zero and four.

For example:
#include <cstdlib> // Include rand()

using namespace std; // Make rand() visible

int a = rand(); // rand is a standard function that all compilers have</cstdlib>

DO..WHILE loops are useful for things that want to loop at least once. The structure is
do {
} while ( condition );

while ( condition ) { Code to execute while the condition is true } The true represents a boolean expression which could be x == 1 or while ( x != 7 ) (x does not equal 7). It can be any combination of boolean statements that are legal. Even, (while x ==5 || v == 7) which says execute the code while x equals five or while v equals 7. Notice that a while loop is the same as a for loop without the initialization and update sections. However, an empty condition is not legal for a while loop as it is with a for loop.

Example:
#include <iostream>

using namespace std; // So we can see cout and endl

int main()
{
int x = 0; // Don't forget to declare variables

while ( x < 10 ) { // While x is less than 10
cout<< x <<endl;
x++; // Update x so the condition can be met eventually
}
cin.get();
}</endl;
</iostream>

for ( variable initialization; condition; variable update ) {
Code to execute while the condition is true
}

A. !( 1 || 0 ) ANSWER: 0
B. !( 1 || 1 && 0 ) ANSWER: 0 (AND is evaluated before OR)
C. !( ( 1 || 0 ) && 0 ) ANSWER: 1 (Parenthesis are useful)

if ( <condition> ) {
// Execute these statements if <condition> is TRUE
}
else if ( <another condition=""> ) {
// Execute these statements if <another condition=""> is TRUE and
// <condition> is FALSE
}</condition></another></another></condition></condition>

It can look like this:

if ( TRUE ) {
// Execute these statements if TRUE
}
else {
// Execute these statements if FALSE
}

The structure of an if statement is as follows:
if ( TRUE )
Execute the next statement

Here is a simple example that shows the syntax:
if ( 5 < 10 )
cout<<"Five is now less than ten, that's a big surprise";

Here are the relational operators, as they are known, along with examples:
> greater than 5 > 4 is TRUE
< less than 4 < 5 is TRUE
>= greater than or equal 4 >= 4 is TRUE
<= less than or equal 3 <= 4 is TRUE
== equal to 5 == 5 is TRUE
!= not equal to 5 != 4 is TRUE

Here is a sample program demonstrating the use of a variable:

#include <iostream>

using namespace std;

int main()
{
int thisisanumber;

cout<<"Please enter a number: ";
cin>> thisisanumber;
cin.ignore();
cout<<"You entered: "<< thisisanumber <<"n";
cin.get();
}</iostream>

To declare a variable you use the syntax "type <name>". Here are some variable declaration examples:
1- int x;
2- char letter;
3- float the_float;
It is permissible to declare multiple variables of the same type on the same line; each one should be separated by a comma.
1- int a, b, c, d;
If you were watching closely, you might have seen that declaration of a variable is always followed by a semicolon (note that this is the same procedure used when you call a function).</name>

for( unsigned int i = 1; i < = 100; i++ )
if( i & 0x00000001 )
cout << i << ",";

i want to say Global scope(int i = 111;),Local scope (int i = 333;), and function scope (int i = 222;) but now, i\'m confused. I really don\'t understand what is this question asking me. Can somebody help me break it down

Whichever one works best for the organization.
We believe in honesty, not advocacy, and the honest answer is that there
is no single answer. What is the organization’s policy regarding languages?
Must there be one and only one official language? What is the skill level of
the staff? Are they gung-ho developers with advanced degrees in computer
science/engineering or people who understand the business and have survival
skills in software? Do they already have OO skills? In which language(s)? What
sort of software development is being done: extending someone else’s framework
or building from scratch for resale? What sort of performance constraints does
the software have? Is it space constrained or speed constrained? If speed, is it
typically bound by I/O, network, or CPU? Regarding libraries and tools, are
there licensing considerations? Are there strategic partnership relationships that
affect the choice of languages? Many of these questions are nontechnical, but
they are the kind of questions that need to be answered the “which language”
issue can be addressed.
Regarding the choice between C++ and Java, java is a simpler language and
thus it is generally easier to use. However C++ is more established and allows
finer control over resources (for example, memory management), and this is required
for some applications. Also, C++ has language features such as destructors

The Software Peter Principle is in operation when unwise developers “improve” and “generalize” the software until they themselves can no longer understand it, then the project slowly dies.
The Software Peter Principle can ruin projects. The insidious thing about the Software Peter Principle is that it’s a silent killer — by the time the symptoms are visible, the problem has spread throughout every line of code in the project.
Foolish managers deal with symptoms rather than prevention, and they think
everything is okay unless there are visible bugs. Yet the problem isn’t bugs, at least initially. The problem is that the project is collapsing under its own weight.
The best way to avoid this problem is to build to the skill level of the maintainers, not of the developers. If the typical maintainer won’t understand the software then it’s simply too complex for the organization to maintain. This means avoiding tricky, sophisticated, subtle, clever techniques unless there is a compelling reason for them. Cleverness is evil; use it only when necessary.
Shown concern for the long-term health of the system being developed.

Unnecessary complexity — the plague of OO technology.
Complexity, like risk, is a fact of life that can’t be avoided. Some software
systems have to be complex because the business processes they represent are
complex. But unfortunately many intermediate developers try to “make things
better” by adding generalization and flexibility that no one has asked for or will
ever need. The customer wants a cup of tea, and the developers build a system
that can boil the ocean [thanks to John Vlissides for this quip]. The result
is unnecessary complexity, which increases the risk of failure. The intentions
might be good but the result can be deadly.
Here are a few guidelines.
• Don’t solve problems that don’t need to be solved.
• Don’t worry about the future until you’re sure you can survive the present.
39
• Don’t build things for the fun of it.
• The organization’s health is more important than the developer’s desire
to play with the latest whiz-bang tool or technique.
• Don’t add risk without a compelling and measurable benefit to the project.
• Don’t invest in the future if your current project is in trouble.
Avoid the “death by one thousands cut” syndrome by avoiding unnecessary
complexity.

C++ extends the variable declaration syntax from built-in types (e.g., int
i;) to objects of user-defined types. The syntax is the same: TypeName VariableName.
For example, if the header file “Car.hpp” defines a user-defined type called Car,
objects (variables) of class (type) Car can be created:
#include "Car.hpp" // Define class Car
void f()
{
Car a; // 1: Create an object
a.startEngine(); // 2: Call a member function
a.tuneRadioTo("AM", 770); // 3: Call another member function
} // 4. Destroy the object
int main()
{
f();
}
When control flows over the line labeled 1: Create an object, the runtime
system creates a local (auto) object of class Car. The object is called a and can
be accessed from the point where it is created to the } labeled 4: Destroy the
object.
When control flows over the line labeled 2: Call a member function, the
startEngine() member function (a.k.a. method) is called for object a. The
compiler knows that a is of class Car so there is no need to indicate that the
proper startEngine() member function is the one from the Car class. For
example, there could be other classes that also have a startEngine() member
function (Airplane, LawnMower, and so on), but the compiler will never get
confused and call a member function from the wrong class.