invalid initialization of non-const reference of type ‘std::string& -

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i trying trim string using function rtrim() string header in c++ without using algorithm. did examine start , end position if there space exist, delete out using isspace() when compile, error: invalid initialization of non-const reference of type ‘std::string& {aka std::basic_string&}’ rvalue of type ‘const char*’

and here code

#include <iostream> #include <string> using namespace std;  string rtrim(string& s) { size_t i; for(i = s.length() - 1; != (size_t)-1; i--) {         if(!(isspace(s[i]))){         break;         }     } return s.substr(0, + 1); }  int main(){     cout << "|" << rtrim("   hello world\t ") << "|" << endl; }

whenever set parameter such string s = ( "hello world\t "); , run cout << rtrim(s) << endl; seems working doesn't work above code. suggestions? thank you.

the above code create temporary object of std::string on stack , pass function non-const reference. dangerous function modify object (which doesn't make sense) or remember reference object , try modifying out of scope once object destroyed.

in function don't require non-const reference, change parameter const std::string &s , work.


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