CODEWITHSUNDEEP
c++arraysstringchar
Acronym TheRapper
Acronym TheRapper

Reputation: 25

(C++) Replacing any value of array found in string with corresponding values of other array?

I've tried all kinds of things. Unfortunately, I don't keep previous records of code so I'll just show you what I have currently:

    string l2n(std::string input) {
    std::string original[26] = {"A","B","C","D","E", "F", "G", "H", "I", "J", "K," "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};
    //std::string originalLower[26] = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    std::string newval[26] = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26"};
    string neworig = (original[0], original[1], original[2], original[3], original[4], original[5], original[6], original[7], original[8], original[9], original[10], original[11], original[12], original[13], original[14], original[15], original[16], original[17], original[18], original[19], original[20], original[21], original[22], original[23], original[24], original[25]);
    string newnewval = (newval[0], newval[1], newval[2], newval[3], newval[4], newval[5], newval[6], newval[7], newval[8], newval[9], newval[10], newval[11], newval[12], newval[13], newval[14], newval[15], newval[16], newval[17], newval[18], newval[19], newval[20], newval[21], newval[22], newval[23], newval[24], newval[25]);
    size_t posit = input.find(neworig.c_str());
    string hash2345;
    hash2345 = input.replace(posit, std::string(neworig).length(), newnewval.c_str());
    return hash2345;
}

That compiles fine, but outputs "26HELLO" with my input "HELLO". It literally just appends 26 to the beginning of any input given..I'm guessing it has something to do with the usage of input.replace using the length, but I don't know what else to do and google isn't finding anything. Thanks for your help!

Upvotes: 0

Views: 562

Answers (2)

Tyler McHenry
Tyler McHenry

Reputation: 76660

I think you are misunderstanding what string::replace does. It does not replace characters in one string with the equivalently positioned characters in another. It replaces a span of characters in one string with the entirety of another string.

For example,

std::string test = "This is a test.";

// Replace 2 characters, starting at position 5 with "was"
test.replace(5, 2, "was");

std::cout << test;  // Outputs "This was a test."

For what you are doing, you will need a loop that performs an action on each character in your input, e.g.

string hash2345;

// For each character in input
for (int i = 0; i < input.length(); ++i) {

  // Try to find the string equal to the i'th character of input in 
  // the "original" array.
  string* original_val_ptr = std::find(original, original + 26, 
                                       std::string(input[i]));

  // Make sure that it actually found something (this handles the case
  // where input has some other characters, like lowercase or punctuation).
  if (original_val_ptr != NULL) {

    // Find the position of this value in the original array.
    size_t pos = original_val_ptr - original;

    // Add the string in the equivalent position in the "newval" array
    // to the output.
    hash2345 += newval[pos];
  }
}

return hash2345;

Now there are a number of additional improvements that can be made to your code, and I'm sure that other answers will suggest them, but given that you seem to be a relatively new programmer, I am choosing to keep this answer as straightforward as possible and focus only on the correctness of the algorithm that you are apparently trying to implement.

Also, this will work for any mapping of one set of characters to another, even if it is not letters to numbers.

Upvotes: 1

john
john

Reputation: 8027

Based on the comments above, and assuming you are using ASCII, then the following does what you want

string l2n(std::string input)
{
    ostringstream buf;
    for (string::const_iterator i = input.begin(); i != input.end() ++i)
    {
        buf << (*i - 'A') + 1;
    }
    return buf.str();
}

Upvotes: 0

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