Programming String Manipulation (Edexcel GCSE Computer Science)

Revision Note

Author

James Woodhouse

Expertise

Computer Science

Programming String Manipulation

What is string manipulation?

String manipulation is the use of programming techniques to modify, analyse or extract information from a string
Examples of string manipulation include:
- Length (analyse)
- Position (analyse)
- Substrings (extract)
- Case conversion (modify)
- Concatenation (modify)

Length

The ability to count the number of characters in a string, for example, checking a password meets the minimum requirement of 8 characters

Function	Python	Output
Length	`Password = "letmein"` `print(len(Password))`	7
`Password = "letmein"` `if len(Password) >= 8:` `print("Password accepted")` `else:` `print("Password too short")`	"Password too short"

Function

Python

Output

Length

Password = "letmein"

print(len(Password))

Password = "letmein"

if len(Password) >= 8:

print("Password accepted")

else:

print("Password too short")

"Password too short"

Position

Position refers to the index or location of a character in a string
positions in strings, just like arrays, are 0 indexed (the first value is 0, not 1)
A position of a certain word of character from a string can be found using the following:
- words = "Hello, World!"
  Find the position of the letter e
  print(words.index('e'))
- The output would be 1

Substring

Substring and slicing perform similar tasks in programming
Substring is the ability to extract a sequence of characters from a larger string to be used by another function in the program, for example, data validation or combining it with other strings
Extracting substrings is performed using 'slicing', using a specific start and end to slice out the desired characters
Substring is 0 indexed

Function	Python	Output
Substring	string[start character : end character]
	`Word = "Revision"` `print(Word[2:5])`	"vis"
	left(number of characters)
	`Word = "Revision"` `print(Word[:4])`	"Revi"
	right(number of characters)
	`Word = "Revision"` `print(Word[4:])`	"sion"

Case conversion

The ability to change a string from one case to another, for example, lower case to upper case

Function	Python	Output
Uppercase	`Name = "Sarah"` `print(Name.upper())`	"SARAH"
Lowercase	`Name = "SARAH"` `print(Name.lower())`	"sarah"
Title case	`Book = "inspector calls"` `print(Book.title())`	"Inspector Calls"

Function

Python

Output

Uppercase

Name = "Sarah"

print(Name.upper())

"SARAH"

Lowercase

Name = "SARAH"

print(Name.lower())

"sarah"

Title case

Book = "inspector calls"

print(Book.title())

"Inspector Calls"

Concatenation

The ability to join two or more strings together to form a single string
Concatenation uses the '+' operator to join strings together

Function	Python	Output
Concatenation	`FName = "Sarah"` `SName = "Jones"` `FullName = FName + SName` `print(FullName)`	"SarahJones"
`FName = "Sarah"` `SName = "Jones"` `FullName = FName + " " + SName` `print(FullName)`	"Sarah Jones"
`Name = "Sarah"` `print("Hello, " + Name)`	"Hello, Sarah"

Function

Python

Output

Concatenation

FName = "Sarah"

SName = "Jones"

FullName = FName + SName

print(FullName)

"SarahJones"

FName = "Sarah"

SName = "Jones"

FullName = FName + " " + SName

print(FullName)

"Sarah Jones"

Name = "Sarah"

print("Hello, " + Name)

"Hello, Sarah"

Exam Tip

Remember that the '+' operator is used for concatenation of strings BUT is also the mathematical operator for addition

It is important to remember, that the same operator symbol performs different roles on different types of data (integer/string)

Worked Example

A school wants to use a program to take a students first name, last name and year of entry as inputs and use them to create a username

They want the username to follow the rule:

Initial + First 3 letters of last name + year

For example, a student named David Hamilton who started in 2024 would have the username:

DHam2024

The algorithm has been started below:

Line	Algorithm
01	`FName = input("Enter first name")`
02	`LName = input("Enter last name")`
03	`year = input("Enter year")`
04	`username =`
05	`print(username)`

Use string manipulation to complete line 04 to create the username [3]

How to answer this question

What techniques do we need to use to create the username? substring to extract the parts of the first and last name
Concatenation to join them together

Answer

Line	Algorithm
01	`FName = input("Enter first name")`
02	`LName = input("Enter last name")`
03	`year = input("Enter year")`
04	`username = FName.substring(0,1) + LName.substring(0,3) + year`
05	`print(username)`

FName.substring(0,1) 1 mark
LName.substring(0,3) 1 mark
username = FName.substring(0,1) + LName.substring(0,3) + year 1 mark

You've read 0 of your 0 free revision notes

Get unlimited access

to absolutely everything:

Downloadable PDFs
Unlimited Revision Notes
Topic Questions
Past Papers
Model Answers
Videos (Maths and Science)

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Next topic

Did this page help you?

Programming String Manipulation (Edexcel GCSE Computer Science)

Revision Note

Programming String Manipulation

What is string manipulation?

Length

Position

Substring

Case conversion

Concatenation

Exam Tip

Worked Example

You've read 0 of your 0 free revision notes

Get unlimited access

Join the 100,000+ Students that ❤️ Save My Exams

Author: James Woodhouse