Arrays in Programming

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Questions and Answers

What is the purpose of the sprintf() function in the provided program?

It generates random digits for user IDs.

It converts formatted data to an array of characters. (correct)

It displays the formatted string directly to the user.

It takes user input for integers and doubles.

How many random digits are appended to the username?

2 digits

1 digit

4 digits

3 digits (correct)

What is the maximum length of the username as defined in the program?

8 characters

80 characters

9 characters (correct)

10 characters

What ensures the userID string is properly terminated in the program?

Explicitly placing a null character '\0' at the end. Signup and view all the answers

What could the output be if the user enters 'John Doe' for their name?

User ID with 3 random digits prefixed by 'Joh'. Signup and view all the answers

Which function is case-sensitive in string comparisons?

strncmp() Signup and view all the answers

How does the program generate the random digits for the username?

By using the rand() function. Signup and view all the answers

What will be the value of studentId[0] after the initialization loop is executed?

1 Signup and view all the answers

What is the maximum index for the array studentId defined with MAX_STUDENTS?

9 Signup and view all the answers

What is the effect of using 'scanf()' with a format that limits input size?

It prevents buffer overflow by limiting characters read. Signup and view all the answers

What type of elements does the array studentId hold?

int Signup and view all the answers

Which of the following statements is true about multi-dimensional arrays?

They can have multiple rows and columns. Signup and view all the answers

How can the studentId array be defined using an initializer list?

int studentId[MAX_STUDENTS] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; Signup and view all the answers

What is the purpose of using a loop to initialize an array?

To assign values systematically to each element. Signup and view all the answers

In the statement `c[a+2] += 2;`, what does `a` represent?

A constant value of 1. Signup and view all the answers

What happens if you try to access studentId[10] in the defined array?

It causes a runtime error. Signup and view all the answers

What is the purpose of using the conversion specifier %9s in the scanf function?

To ensure the last character is saved as a null character. Signup and view all the answers

What happens if more than 9 characters are entered using the scanf function without handling it properly?

It may cause a buffer overflow and crash the program. Signup and view all the answers

Which standard I/O function is used to read characters into an array until a newline is encountered?

fgets Signup and view all the answers

What will getchar() return if it reaches the end-of-file?

An integer representing EOF Signup and view all the answers

How does the while loop within the main function read characters?

It reads until a newline is encountered and a maximum limit. Signup and view all the answers

What does the puts() function do when called with a string as an argument?

It prints a string followed by a newline character. Signup and view all the answers

What character is used to mark the end of a string in C?

'\0' Signup and view all the answers

What is the purpose of a function prototype in programming?

To inform the compiler of the function's return type and parameters Signup and view all the answers

Where are function prototypes typically declared?

At the top of a source file or in a header file Signup and view all the answers

What follows the keyword 'return_value_type' in a function definition?

The function's name Signup and view all the answers

What does the function `addition(int, int)` primarily indicate?

The function accepts two integer parameters and returns an integer Signup and view all the answers

What is the role of 'scanf' in the provided code example?

To read input values from the user Signup and view all the answers

Which of the following is incorrect regarding function definitions?

Function parameters must not have explicitly defined types Signup and view all the answers

What is an integer result expected from the 'addition' function?

An integer value Signup and view all the answers

Which statement about function calls is true?

Function calls must match the parameter list in types and order Signup and view all the answers

What is the scope of the variable 'i' when it is declared outside any function?

File scope Signup and view all the answers

What does the update to 'i' in the function 'add_i' demonstrate?

Global variable tracking Signup and view all the answers

At what value does 'i' end after the function 'add_i' is called once from 'main'?

2 Signup and view all the answers

Which of the following statements about block scope is true?

Block scope is limited to the braces that define it. Signup and view all the answers

What is the purpose of the 'printf' function within ‘main’?

To print the current value of 'i' Signup and view all the answers

Which of these describes the way an array is structured?

Multiple memory locations sharing the same name and type Signup and view all the answers

What is the initial value of the subscript (index) in an array?

0 Signup and view all the answers

What will the output of 'add_i' return when called with 4 based on the defined functions?

5 Signup and view all the answers

Study Notes

Arrays

An array is a collection of memory locations
All locations in the array have the same name and data type
Array elements can be accessed using an index
The index starts at zero and can be any integer expression
The maximum index in an array is the number of elements minus 1

Defining Arrays

An array can be defined using the keyword int followed by the name of the array and the number of elements in square brackets
Example: int studentId[MAX_STUDENTS];

Array Initialisation

Arrays can be initialised with a loop or using an initialiser list
Loop example:
- Define an array: int studentId[MAX_STUDENTS];
- Initialize the array: for (int i = 0; i < MAX_STUDENTS; i++) { studentId[i] = i + 1; }
Initialiser list example:
- Define and initialize: int studentId[MAX_STUDENTS] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

Multi-Dimensional Arrays

Multi-dimensional arrays can be used to represent data with multiple dimensions
The most common is a two-dimensional array, which can be thought of as a table with rows and columns
An array with m rows and n columns is called an m-by-n array

String Initialisation

Strings can be stored in an array using the scanf function
Use a conversion specifier like %9s with scanf to read up to 9 characters, making sure the final character is the null character '\0'
Example: char word; scanf("%9s\n", word);
Be mindful of exceeding the array length when reading strings, as it could lead to program crashes

Standard I/O Functions for strings & characters

fgets()
- Reads characters from a file or stream into a character array
- Stops reading when it reaches a newline character (\n), the end-of-file indicator, or the specified maximum number of characters
puts()
- Prints a string to the standard output, adding a newline character after the string
getchar()
- Reads a single character from the standard input and returns it as an integer value
sprintf()
- Prints formatted data into an array of characters, similar to printf using the same conversion specifiers

String Manipulation Library Example

This program generates a user ID based on the user's full name
It uses several string manipulation functions:
- strncpy() copies a specified number of characters from one string to another
- strlen() calculates the length of a string
- rand() and srand() for generating random numbers

String Comparison Functions

strcmp() and strncmp() are case-sensitive functions for comparing strings
strcmp() compares two whole strings
strncmp() compares a specified number of characters from two strings

Functions and function prototypes

Functions are blocks of code that perform specific tasks and can be reused
Functions can receive input parameters and return a value
A function prototype is a declaration of a function without its body
Prototypes inform the compiler about the function's return type, name, and parameters
Example: int square(int);
Prototypes can be declared at the top of a source file or in a header file

Scope Rules

File Scope: Variables declared outside any function have file scope, making them accessible throughout the program.
Block Scope: Variables declared inside a block delimited by braces {} have block scope, making them only accessible within that block.
Example:
- int i = 1; (file scope)
- int x = 4; (block scope within main())
- int x = n + i; (block scope within add_i())
- i++; (updates the global variable i)
Variables with block scope are often called local variables.

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Description

This quiz covers the fundamental concepts of arrays in programming, including definition, initialization, and multi-dimensional arrays. Test your understanding of how to define and access array elements using indices, as well as methods for initializing arrays in your code.