Important Short Questions and Answers: C Programming Advanced Features

1. Compare arrays and structures.

2. Compare structures and unions.

3. Define Structure in C.

A structure contains one or more data items of different data type in which the individual elements can differ in type.

A simple structure may contain the integer elements, float elements and character elements etc. and the individual elements are called members.

Example:             struct result

{

int marks;

float avg;

char grade;

}std;

4. Rules for declaring a structure?

A structure must end with a semicolon.

Usually a structure appears at the top of the source program.

Each structure element must be terminated.

The structure must be accessed with structure variable with dot (.) operator.

5. Define structure pointers

Pointer is a variable, it contain address of another variable and the structure pointers are declared by placing * in front of a structure variable‟s name.

Example:             struct result

{

int marks;

float avg;

char grade;

};

struct result *sam;

6. Define union?

A union, is a collection of variables of different types, just like structure. Union is a derived data type and the difference between union and structure is in terms of storage.

In structure each member has its own storage location, whereas all the members of union use the same memory location.

Example:             union result

{

int marks;

float avg;

char grade;

}std;

7. Define file?

A file is a collection of bytes stored on a secondary storage device, which is generally a disk of some kind. The collection of bytes may be interrupted, for example, as characters, words, lines, paragraph and pages from a textual document.

Example:             FILE *infile;

FILE *outfile;

8. Define binary files?

Binary files can be processed sequentially or, depending on the needs of the application, they can process using random access techniques.

In C, processing a file using random access techniques involves moving the current file position to an appropriate place in the file before reading or writing data.

9. Define opening a file?

A file requires to be opened first with the file pointer positioned on the first character. No input-output functions on a stream can be performed unless it is opened.

When a stream is opened, it is connected to named DOS device or file .C provides a various functions to open a file as a stream.

Syntax:                FILE *fopen(char * filename, char *mode);

10. Define fseek()?

fseek() will position the file pointer to a particular byte within the file. The file pointer is a pointer is a parameter maintained by the operating system and determines where the next read will comes from , or to where the next write will go.

11.            Functions of bit fileds?

Bit fields do not have address.

  It is not an array.

  It cannot be accessed using pointer.

  It cannot be store values beyond their limlits. If larger values are assigned, the output is undefined.

12.            What are the ways to detecting End of File?

In Text file:

Special character EOF denotes the end of file.

As soon as character is read, end of the file can be detected

EOF is defined in stdio.h

Equivalent value of EOF is -1

In binary file:

feof function is used to detect the end of file

it can be used in text file.

feof returns TRUE if end of the file is reached

Syntax:      int feof(FILE *fp);

13.         What are key functions required to process a file?

fopen

  fclose

  fseek

  fread

  fwrite

13.                        List out the file handling functions

fopen()-create a new file or open a existing file fclose-close a file

getc()-reads a character from a file putc()-writes a character to file fscanf()-reads a set of data from a file