CS111 Introduction to Programming - Lecture 4

CS111 Introduction to Programming

• Course title: CS111 Introduction to Programming
• Institution: MedTech, Mediterranean Institute of Technology
• Date: 11/27/2024

Working with Arrays & Strings - Lecture 4

• Topic: Arrays
• Definition: A collection of similar data types or entities stored in contiguous memory locations.
• Advantages:
  • Code optimization: less code to access data.
  • Easy to traverse data: using a for loop, elements can be retrieved easily.
  • Easy to sort data: sorting the array elements requires few lines of code.
  • Random access: any element can be accessed randomly.
• Disadvantages:
  • Fixed size: the size defined at declaration cannot be exceeded.
• Declaration:
  • data type variable_name [size]; (e.g., int arr[10];)
  • Index starts at 0 (e.g., arr[0], arr[9]).
  • Symbolic constants can be used for size (e.g., #define SIZE 10).
• Initialization
  • Arrays must be initialized after declaration. Otherwise, they contain garbage values.
  • Syntax: data type array_name[size]= {value1, value2...};
  • Example: int age[5]={22,25,30,32,35};
• Accessing Array Elements
  • Direct access (e.g., arr[2])
  • Loops for iterative access (e.g., for loop)

Working with Arrays & Strings - Lecture 4

• Topic: Strings

• Definition: an array of characters terminated by a null character (\0)

• Always enclosed by double quotes (" ") for strings

• In C, you use character arrays to represent strings

• Declaration

  • char string_name[size]; The size determines the number of characters that the string can store including the null terminator(\0).

• Initialization

  • Initialize only the required number of characters. The remaining slots are automatically initialized with NULL
    • Example: char str[5]={'H', 'e'};

• Reading and Writing strings

  • Use scanf("%s", &variable) to read a string from the input.
  • Use printf("%s",variable) to write a string to the output.

• String Library Functions:

  • strlen(): returns the length of the string.
  • strcpy(): copies one string to another.
  • strcat(): appends one string to another.
  • strlwr(): converts a string to lowercase.
  • strupr(): converts a string to uppercase.
  • strrev(): reverses a string.
  • strcmp(): compares two strings.

• Unformatted Input/Output:

  • getchar(): reads a single character from the standard input.
  • putchar(): writes a single character to the standard output.
  • getch(): reads a character without echoing to the screen.
  • getche(): reads a character and echoes to the screen.
  • getc()
  • putc()
  • getche(): reads characters without echoing to the screen, commonly used in password programs.

• Exercises:

  • Program to sort an array of elements.
  • Program to determine the second largest element in an array.
  • Program to sum two matrices.
  • Program to count number of alphabet, digits and special characters.
  • Program to determine the maximum occurring character in a string.

This quiz focuses on Lecture 4 of the CS111 Introduction to Programming course, covering the fundamental concepts of arrays. Explore the definitions, advantages, disadvantages, declaration, and initialization of arrays to strengthen your understanding of this essential data structure.