Lecture: String Manipulation in Delphi (Part 1)

Introduction

• Focus: How to manipulate strings using built-in functions in Delphi.
• Definition: A string in Delphi is a sequence of characters (text and numbers).

Basics of Strings

• Strings consist of individual characters, each with a unique position and ASCII value.
• Example: String sTemp with value "Hello World".
  • Position 1: 'H'
  • Position 2: 'E'
  • Position 5: 'O'
  • Position 6: ' '

Accessing Characters in a String

• Use square brackets to access a specific character in a string.
  • Example: sTemp[5] returns 'O'.

Built-in String Functions

Functions Returning Integers

1. Length Function

   • Returns the length of the string.
   • Syntax: Length(sTemp) returns an integer.
   • Example: Length("Hello World") returns 11.

2. Pos Function

   • Returns the position of a substring within a string.
   • Takes two string parameters: substring and string to search.
   • Example: Pos("WR", sTemp) returns 7.
   • Note: Case sensitive. Pos("wr", sTemp) would return 0 if not found.

Functions Returning Strings

1. Copy Function

   • Used to extract a substring from a string.
   • Syntax: Copy(sourceStr, startPos, numChars).
   • Example: Copy(sTemp, 3, 5) results in "llo W".
   • Special Case: If numChars exceeds the string length, it copies up to the end of the string.

2. UpperCase and LowerCase Functions

   • Convert all characters in a string to upper or lower case respectively.
   • Syntax: UpperCase(sTemp) or LowerCase(sTemp).
   • Example:
     • UpperCase("Hello World") becomes "HELLO WORLD".
     • LowerCase("Hello World") becomes "hello world".

Conclusion

• Overview of how to manipulate strings using functions that return integers and strings.
• Mention of upcoming video on string procedures.
• Encouragement to follow up on YouTube, Facebook, and Twitter for more content and updates.