weird problem... (C++)

Question

i am making a Caesar cipher encoder. heres the code:

//////////////////////////////////////////////////////////////////////////////////////

#include <iostream>
#include <string>
#include <map>
using namespace std;

int main(){
map <string,int> charmap = {{"a",0},{"b",1},{"c",2},{"d",3},{"e",4},{"f",5},{"g",6},{"h",7},{"i",8},{"j",9},{"k",10},{"l",11},{"m",12},{"n",13},{"o",14},{"p",15},{"q",16},{"r",17},{"s",18},{"t",19},{"u",20},{"v",21},{"w",22},{"x",23},{"y",24},{"z",25}};
int rot;
string text;
string chars[27] = {"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",};
cout << "enter a value (1 to 23): ";
cin >> rot;
cout << "\n" << "enter some text to encode: ";
cin >> text;
std::cin.ignore();
cout << "\noutput: ";
int size = text.length();
/* debug start*/
cout << "size:" << size <<endl;
cout << "text:" << text <<endl;
/* debug end*/
for (int loop = 0; loop < size; loop++){
string tempchar = text.substr(loop);
if (tempchar == "!") {
cout << " ";
}else {
int temploc = charmap[tempchar];
temploc += rot;
if(temploc>25){
temploc -= 26;
}
cout << chars[temploc];
}
};
return 0;
}
//////////////////////////////////////////////////////////////////////////////////////

when i use it... this happens
input:
1
hello

output:
bbbbp

whats going on?

also c++ only accepts input before white space when using "cin"
for example if i inputted "hello there" it would only get the "hello" part.
is there a way i can bypass it?

Answer 1

see getline() to get whole lines of text. http://www.cplusplus.com/reference/string/string/getline/

Answer 2

Hey there nice code! I haven't actually run it so I'm just guessing, but i think you forgot to give a second, "length" argument to substr():

string tempchar = text.substr(loop);

gives the values

"hello", "ello", "llo", "lo", and "o",

of which only the last one is in the Map, and then when you do the lookups:

int temploc = charmap[tempchar];

you get (because of the way Map::operator[] seems to work):

temploc: 0, 0, 0, 0, 14

and after adding rot:

temploc: 1, 1, 1, 1, 15

which explains the "b"s (and the "p") in cout << chars[temploc];..

..so maybe try:

string tempchar = text.substr(loop, 1); ?

Hope this helps!

@jay Great link to a really useful site (I looked up Map and string::substr there). Thanks!

Answer 3

There is no need of map here. char type is converted to int "under the hood". For example:
char smh = 'a';
smh++;
std::cout << smh; // output: b