I am trying to get the nth element of a string, which I know generally works with a method such as
char current_letter = input_string[j];
However when using the code below I get an output of
0 current_letter: ABC
1 current_letter: BC
2 current_letter: C
ABC BC 9ekNc5GlorW1PkaBQlYCuXMBljdSQClygl00XwKxoVzYsf8FrCs3qUZV85gHJHsl
where the 4th line is just the coded_string variable being printed. This indicates that the std::string current_letter = &input_string[j]; way of trying to get the nth element of the string is not actually returning the nth element but rather everything in the string from the specified index onward.
When I use char instead of std::string to define the current_letter variable (and correspondingly change it from std::string to char in the previous lines defining the std::map and the .insert() method to match, I get an red error line under the .find() method, saying:
no instance of overloaded function "std::map<_Key, _Tp, _Compare, _Alloc>::find [with _Key=std::string, _Tp=std::string, _Compare=std::less<std::string>, _Alloc=std::allocator<std::pair<const std::string, std::string>>]" matches the argument list
I would also like to generally be able to use std::string for both the key and value in the std::map for future purposes, so how would I retrieve the nth letter of the string without any other element in the string being returned?
#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
void set_seed_n_shuffle(std::vector<std::string> &array, unsigned seed){
std::srand(seed);
random_shuffle(std::begin(array), std::end(array));
}
std::string en_to_ch(std::vector<std::string> list, std::string input_string){
// list = ch_list, input_string = string to be converted
std::vector<std::string> en_list = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"};
std::map<std::string, std::string> en_ch_dict;
for (int i=0; i<en_list.size(); i++){
en_ch_dict.insert(std::pair<std::string, std::string>(en_list[i], list[i]));
//en_ch_dict.emplace(en_list[i], list[i]);
}
std::string coded_string;
for (int j=0; j<input_string.size(); j++){
std::string current_letter = &input_string[j];
std::cout << j << " current_letter: " << current_letter << "\n";
if (en_ch_dict.find(current_letter) == en_ch_dict.end()) {
coded_string += current_letter + " "; // not found
} else {
coded_string += en_ch_dict.find(current_letter)->second + " "; // found
}
}
return coded_string;
}
int main(){
std::vector<std::string> ch_list = {"randomcharacters1", "randomcharacters2","randomcharacters3","randomcharacters4","randomcharacters5",}
set_seed_n_shuffle(ch_list, 156);
std::string string_input = "ABC";
std::string new_string = en_to_ch(ch_list, string_input);
std::cout << new_string << "\n";
}
>Solution :
std::string current_letter = &input_string[j];
The current_letter is a single character, not a string. If you construct a string with a pointer to a character, it will read from that character to the end of the string.