unable to solve the error

hello

I am beginner

i just unable to find the errors

my problem is working on visual studio

but not in codechef compiler

please tell me why i am getting error

my code is

#include <iostream>

#include <string>

  using namespace std;

   int main()

  {

	int z,i,l,k,d,T,m;
    
	cin>>T;
	for(m=0;m<=T;m++)
	{
    string hj,str1,str2, str3,ch,s;
	z=0;
	l=0;
	getline(cin,s);
	d=strlen(s);
	str2[0]= '\0';
	for(k=0;s[k]!=d;k++)
    {
    if(s[k]>=65&&s[k]<=90)
	{
    s[k]=s[k]+32;
    }
	}
	
	strcat(hj,s);
	for(i=0;hj[i]!= '\0';i++)
	{
		str3[l]=hj[i];
		l++;
		ch=hj[i];
		if(ch==' ')
	    {

		 str1[0]=hj[z]-32;
		 str1[1]='\0';
		 strcat(str2,str1);
		 strcat(str2,".");
		 z=i+1;
		 l=0;
	    } 
	}
	str3[l]='\0';
	strcat(str2,str3);
	strcat(str2,"\0");
	cout<<str2<<endl;
}
	return 0;
}

You may have selected wrong language . Try using c++14 and replace string with cstring in header file.

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