Session Objectives#U2S11
COULD combine string manipulation in a working program
SHOULD correctly use string manipulation functions
MUST identify built-in string manipulation functions
Create a password strength indicator program
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Key Words
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String Manipulation - Extraction
Most languages have built-in functions to extract part of a
string , often being called LEFT, RIGHT or MID
LEFT (<string>, <number of characters>)
i.E LEFT (“Computing”, 3) returns “Com”
but MID (<string>, <starting position>, <number of characters>)
i.e (“Computing”, 4, 3) returns “put”
TASK:
Experiment with the string extract functions using Python and
then Javascript. Is the syntax and logic the same?
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String Manipulation – Length
Again, ,most languages have a function to calculate the number
of characters in a particular string, usually:
LENGHTH (<string>) i.e LENGTH (<“Computing”>) returns 9
TASK: Try this in Python or Javascript.
It is particularly useful validate passwords and increase
strengths based on the numbers of characters used.
EXT: Design, create and test a program that will encourage
strong passwords to be used. What will you have to do first in
order to write a suitable software solution?
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Password Program
Problem analysis:
The program MUST
• Take user input and store as string
• Measure length of string
• Make decision based on length whether Strong, Medium or
Weak
• Output Decision
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String Manipulation - Locate
Another common in-built function is facilitate the ability to search
a string for certain sequences of characters.
i.e LOCATE (<search string>, <main string>
This varies between
languages
LOACTE (“put”, “Computing”) would return 4 as it is found from
the 4th character along in the string.
TASK: Attempt in Python or Javascript and test to see working by
getting results of 0 and above.
TASK 2: Complete Questions 1-2 in the Activity on p.106
EXT: Create the program in Q3.
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