LESSON 396 OF 413 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: tr v1 — Single Char Swap in C#

Practice

Build a tiny version of the Unix tr command. Given a list of lines and two single characters fromChar and toChar, replace every occurrence of fromChar with toChar in each line, then return the lines joined by newline characters (\n).

Notes: fromChar and toChar are single ASCII characters, taken literally (no escapes like \, no ranges). Upper and lower case are different characters. A line may be empty, and may not contain fromChar at all.

Function signature:

public string Tr(List<string> lines, string fromChar, string toChar)

Example:

Input: lines = ["banana", "apple"], fromChar = "a", toChar = "X"

Output: "bXnXnX\nXpple"

When printed:
bXnXnX
Xpple

C#'s string.Replace(string, string) swaps EVERY occurrence. Apply it to each line and accumulate.

The full solution:

class Solution {
    public string Tr(List<string> lines, string fromChar, string toChar) {
        List<string> result = new List<string>();
        foreach (string line in lines) {
            result.Add(line.Replace(fromChar, toChar));
        }
        return string.Join("\n", result);
    }
}

STEP 1 OF 4

Guided

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CLI Tool: tr v1 — Single Char Swap in C#

Tr V1 in C#