WHat kind of error is this?

#1

terminate called after throwing an instance of ‘std::logic_error’
what(): basic_string::_M_construct null not valid

The error shown is:
#include
#include
#include
using namespace std;

string getStr(string s,int i)
{
char *p=strtok((char )s.c_str()," “);
while(i>1)
{
p= strtok(NULL,” ");
i–;
}
string m=p;
return m;
}
int getint(string s)
{
int sum=0;
for(int i=0;i<s.length();i++)
{
sum=sum10+(s[i]-‘0’);
}
return sum;
}
bool numeric(const pair<string,string>& a,const pair<string,string>& b)
{
string c=a.second;
string d=b.second;
return getint©<getint(d);

}
bool lexico(const pair<string,string>& a,const pair<string,string>& b)
{
string c=a.second;
string d=b.second;

return c<d;
}

int main()
{
int n;
cin>>n;
string s[n];
for(int i=0;i<n;i++)
{
getline(cin,s[i]);
}
int key;
string rev,type;
cin>>key>>rev>>type;
pair<string,string> pr[n];
for(int i=0;i<n;i++)
{
pr[i].first=s[i];
pr[i].second=getStr(s[i],key);
}
if(type==“lexicographical”)
sort(pr,pr+n,lexico);
else
sort(pr,pr+n,numeric);

if(rev=="true")
{
  for(int i=0;i<n/2;i++)
  {
    swap(pr[i],pr[n-1-i]);
  }
}
for(int i=0;i<n;i++)
{
	cout<<pr[i].first<<endl;
}
return 0;

}

#2

@rajarshib03 The problem is the two return 0; statements in your function. The function returns a std::string, which has no constructors that accept an int as input. But, it does have a constructor that accepts a const char * pointer, which 0 is implicitly convertible to. However, constructing a std::string with a null char * pointer is undefined behavior, and your implementation has chosen to throw a std::logic_error exception that you are not catching in your code.

1 Like
#3

#include
#include
#include
using namespace std;

string getStr(string s,int i)
{

char *p=strtok((char )s.c_str()," “);
while(i>1)
{
p=strtok(NULL,” ");
i–;
}
string m§;
return m;
}
int getint(string s)
{
int sum=0;
for(int i=0;i<s.length();i++)
{
sum=sum10+(s[i]-‘0’);
}
return sum;
}
bool numeric(const pair<string,string>& a,const pair<string,string>& b)
{
string c=a.second;
string d=b.second;
return getint©<getint(d);

}
bool lexico(const pair<string,string>& a,const pair<string,string>& b)
{
string c=a.second;
string d=b.second;

return c<d;
}

int main()
{
int n;
cin>>n;
string s[n];
for(int i=0;i<n;i++)
{
getline(cin,s[i]);
}
int key;
string rev,type;
cin>>key>>rev>>type;
pair<string,string> pr[n];
for(int i=0;i<n;i++)
{
pr[i].first=s[i];
pr[i].second=getStr(s[i],key);
}
if(type==“lexicographical”)
sort(pr,pr+n,lexico);
else
sort(pr,pr+n,numeric);

if(rev=="true")
{
  for(int i=0;i<n/2;i++)
  {
    swap(pr[i],pr[n-1-i]);
  }
}
for(int i=0;i<n;i++)
{
	cout<<pr[i].first<<endl;
}
return 0;

}

#4

Some part of your code is not visible here. Could you please share me a link of your codepair.

1 Like
#5

Please send your code link.

#6

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1 Like