isralruval 0 Newbie Poster

i have the following function which works, its encrypts a text file, well its suppose to shift the letters of a text file by whatever the user wants, lets say the text file says "zoo" if the user wants to shift the letters by 1 to the right the output of it should say "app"
but lets say i want to shift it 13 to the right, it wont give the correct results
instead of giving me "mbb" it gives me something random it outputs "\207bb"
anyone wants to help me fix it??

void rotateEncrypt(vector<string> V1, vector<string> V2, int rotKey)
{
char ch;
int k;
string word = V1[0];
for (unsigned i=0; i<word.size();i++)
{
if(word[i]!=' '){
ch = tolower( word[i]);
ch = ch + rotKey;
if(ch > 'z')ch = 'a' + (ch - 'z' -1);
word[i] = ch;
}
}
V2.push_back(word);
ofstream fo("simpler.txt" ,ios::app);
fo<< word <<'\n';
fo.clear();
fo.close();
}