LESSON 392 OF 409 · 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:

string tr(vector<string> lines, string fromChar, string toChar)

Example:

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

Output: "bXnXnX\nXpple"

When printed:
bXnXnX
Xpple

Walk each line character-by-character. For each char, append toChar[0] if it equals fromChar[0], otherwise append the original character.

for (int j = 0; j < lines[i].size(); j++) {
    if (lines[i][j] == fromChar[0]) result += toChar[0];
    else result += lines[i][j];
}

The full solution:

class Solution {
public:
    string tr(vector<string> lines, string fromChar, string toChar) {
        string result;
        for (int i = 0; i < lines.size(); i++) {
            if (i > 0) result += "\n";
            for (int j = 0; j < lines[i].size(); j++) {
                if (lines[i][j] == fromChar[0]) result += toChar[0];
                else result += lines[i][j];
            }
        }
        return result;
    }
};

STEP 1 OF 7

Guided

Ctrl + Enter to check

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

Tr V1 in C++