C and C++ Programming Fundamentals

The ceil function returns the smallest integral value greater than or equal to x. The result will be 10.000.

The C for statement has the following form:

for(start;condition;increment/decrement)   {}
In the statement given above since, nothing has been specified the for loop, it  will run infinitely. To terminate such a loop the 'ctrl+break' key combination should be pressed.

The call by reference method of passing arguments to a function copies the reference of an argument into the formal parameter. Inside the function, the reference is used to access the actual argument used in the call. This means that changes made to the parameter affect the passed argument. The ampersand(&) sign is used to denote pass by reference.

The fseek() is used to move the pointer at any position in a file. It is used in programs where we want to read or write data from/to a specific position in a file. It has the following syntax -
fseek(filepointer,int bytes,int offset)
where
file pointer is a pointer pointing to a file.
bytes - is the number of bytes that we want to move.
offset - denotes the position from where we want to move.for example 
fseek(fp,10,0)
will move the pointer 10 bytes from the beginning.

Although most of the programs can be made using inbuilt functions like printf(), scanf(), the user has the option of declaring his own functions. Such functions are known as user defined functions. The main objective of a user defined function is to save time and effort since,  a method can be called as many times as required.

Tokens are individual words and punctuation marks in passage of text. In C, program the smallest individual units are known as C Tokens. C has Six types of Tokens - Keywords,  Strings, Identifiers, Operators, Constants and special symbols.

The strcmp function compares the contents of two strings and returns a value indicating whether they are same or not. It can return the following values :
< 0 - If string1 is less than string2
> 0  - If  string2 is less than string1  
0    -   If string1 is equal to string2
Strcmp considers the case of the string during comparison.

The -> (arrow) operator is used to reference individual members of a structures.The arrow operator is used with a pointer to an object. For example, if 'stud' is a pointer object pointing to a structure 'student', then the following statement can be used to access the member of the structure.
printf("%d",*s->rollno);

The value to be compared should be of integral type. We cannot compare a floating point value using a switch-case.

The a+ mode opens a text file for reading and writing both. It creates the file if it does not exist. The reading will start from the beginning but writing can only be appended.

A dequeue (Double Ended Queue) is a data structure in which elements can be added or removed from the ends (front or rear). Elements of a deque can be scattered in different groups of storage, with the container keeping the necessary information internally to provide direct access to any of its elements in constant time and with a uniform sequential interface.

The typedef keyword can be used to give a new name to a data type. For example,
typedef int number;
The above statement will change the name of the 'int' type to 'number'. Therefore to declare an integer varaible we can also use the statement :
number age;

The C library function void perror(const char *str) prints a descriptive error message to stderr. First the string str is printed followed by a colon then a space. Syntax : void perror (const char *str) where str is the user defined message that prints before the actual error message.

Structures can be nested. A structure can contain a reference of another structure. For example :
struct person
{
  char name[10]:
  int age;
};
struct emp
{
int empno;
personal person;
};
In the above code the 'person' variable has a reference of the 'person' structure as its datatype. If an object of the structure 'emp' is declared, we can not only access the member of 'emp' but also of the 'person' structure.

The scope resoultion operator is not a valid C operator. It is used in C++ to specify the scope of a variable or object.

The ++ operator is the pre fix increment operator. The pre increment operator first increments the variable up to break point then starts assigning the final value to all variable. Therefore the statement
x=++i + ++i + ++i;
will translate into
x=5+6+7;
after all the increments are finished, x will have the value 7 since, that is the last value after the statement. Now the final result will be
x=7+7+7
that is 21.

A queue is a data structure which stores the data in First In First Out Mode. A queue consists of two sides - front and rear. The nodes are added from the rear side and removed from the front side just like people join a queue from the end and pull out   from the beginning in a real life queue. The node that was added the first is also the first one to be removed.

When the program closes, operating system automatically releases all the memory allocated by the program but it a good programming practice to release that memory by calling the function free(). The free() function is defined in the header file malloc.h

Deep sort is not a valid sort type.

The preorder traversal of a tree reads the node in root, left, right order. The data of a node will be read first, if the node has a left child node it will be accessed next, followed by the right child node.

The %x specifier is used to print int as hexadecimal values,' x' uses lower-case letters and 'X' uses upper-case.

In main function, definition of func() is not know to the compiler during compilation so it will assume the return type and parameter type to int,  but in definition when it sees the parameter type is float, it throws an error.

The break is used to break out of the case statements. Break is a keyword that breaks out of the code block, usually surrounded by braces, which it is in. In this case, break prevents the program from falling through and executing the code in all the other case statements.