Summary - Advanced strings

Combine Substring, Split and Replace to write a CSV parser.

Summary - Advanced string methods

In this group you learned five commonly used string tools. Substring takes a slice; IndexOf and LastIndexOf give a substring's position; Split and string.Join break apart and merge; Trim and Pad clean and align edges; Replace swaps substrings.

None of them mutate the original; they all return a new string. That is why you should always assign the result to a variable. Most throw if you cross the string's bounds, so checking the -1 return from IndexOf is a good habit.

Combining in practice

In real projects you often use these methods together. You might pull the domain out of an email with IndexOf + Substring, turn a comma-separated list into an array with Split, then clean each item with Trim. Using PadLeft to align output is common.

Recognising these patterns speeds up real text-processing tasks. In the next exercise you will try them all together.

Exercise Clean and align a name list

Split the comma-separated names in raw into an array called names. Use a foreach loop to trim each name with Trim, pad it with PadRight(8) and print it with Console.WriteLine.

Show example solution

Split with names = raw.Split(','); then foreach (string n in names) { Console.WriteLine(n.Trim().PadRight(8)); }
Example solution:
using System;

class Program
{
    static void Main()
    {
        string raw = "alex , mary , john";
        string[] names = raw.Split(',');
        foreach (string n in names)
        {
            Console.WriteLine(n.Trim().PadRight(8));
        }
    }
}

Test yourself

Match each method to its job

Substring

Take a slice
IndexOf

Find first position
Split

Break at separator
Replace

Swap a substring
Which method breaks a string into pieces?
```
string[] parts = "a,b,c".Split(',');
```
- Substring
- Replace
- Split
- Trim
Show answer

Substring — Correct! Split breaks a string around a separator.

Next lesson: Console.ReadLine

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