CODEWITHSUNDEEP
c++
Rhythm Shandlya
Rhythm Shandlya

Reputation: 124

Termination called after throwing an instance 'std::out_of_range'

Their is a runtime error of 'out_of_range'. It works when i use i>0, but my first character does not get added to my string if i do so.

int main(){

string str;
string strR;
short count {0};

getline(cin,str);

int n=str.length();

for(size_t i=n-1;i>=0;i--)
strR.push_back(str.at(i));


    if(str==strR)
    cout<<"Yes\n";
    else
    cout<<"No\n";

return 0;

}

Upvotes: 0

Views: 88

Answers (1)

Daniel Langr
Daniel Langr

Reputation: 23497

For i of type size_t, the condition i >= 0 is always true. After i being zero, negative overflow occurs and i becomes some large number. str.at(i) then naturally throws.

Very simple correction:

for (size_t i = n; i > 0; i--)
   strR.push_back(str.at(i - 1));

Alternatively, you can use a signed type for i, such as int. However, this may then broke for very large strings. I wouldn't use it in production code.

BTW, to check whether a string is a palindrome, you don't need to copy it. Simpler and faster would be just iterating over the half of the string and compare corresponding characters from the second half.

Upvotes: 3

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