C++ char array to int [closed] - c++

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I am new to C++ and I am creating a small program. Part of it I have created a way of converting a char array to set of int's. But i was just wondering if there is a better way (more efficient and/or uses better C++ standards). Like for example using atoi on spliced part of the array for each number for etc.
So I start of reading a set of numbers e.g. "11 2 123 44" from a file into a char * array and now want to convert them into there respective values currently doing it as follows:
//char * char_cipher; //{'1', '1', ' ', '2', ... , '4'}
//int length; //length of char_cipher
string s = "";
vector<int> cipher_int;
for (int i = 0; i <= length; i++) {
if (char_cipher[i] == ' ') {
//create num
cipher_int.push_back(stoi(s));
s = ""; //empty num
}
else {
//add to string
s += char_cipher[i];
}
}
Any help would be much appreciated thanks :)

Answer 1

Your code is pretty close. The problem is that you never push the last number in char_cipher onto cipher_int, because there's no space after it. You need to do an extra check after the loop is done.
for (int i = 0; i <= length; i++) {
if (char_cipher[i] == ' ') {
//create num
cipher_int.push_back(stoi(s));
s = ""; //empty num
}
else {
//add to string
s += char_cipher[i];
}
}
if (s != "") {
cipher_int.push(back(stoi(s));
}

Answer 2

Let the STL do the parsing for you. You can use a std::istringstream for that, eg:
#include <string>
#include <sstream>
#include <vector>
std::string str_cipher; //"11 2 123 44"
std::vector<int> cipher_int;
std::istringstream iss(str_cipher);
int num;
while (iss >> num) {
cipher_int.push_back(num);
}
Alternatively:
#include <string>
#include <sstream>
#include <vector>
#include <algorithm>
#include <iterator>
std::string str_cipher; //"11 2 123 44"
std::vector<int> cipher_int;
std::istringstream iss(str_cipher);
std::copy(
std::istream_iterator<int>(iss),
std::istream_iterator<int>(),
std::back_inserter(cipher_int)
);