hello there, im new in c++...i just want to know how to compare a string to null like:
string x;
cin >> x;
if(x==NULL){
cout << "null";
}im using this one, if(&x==0) ...but it does'nt work...
this is what my mentor told me to do...
help..thanks
Jump to Poststring class has no overloaded "==" operator. You can do
string temp; cin >> temp; if(temp.empty()) cout << "null";
Jump to PostGiven
char temp[100];I guess you must be talking of how to determine is a string is empty. How about something likeif(strlen(temp) == 0) { }.
Jump to PostDoes it work in C++ like this?:
if( *temp_ptr == 0 ) {}
string class has no overloaded "==" operator. You can do
string temp;
cin >> temp;
if(temp.empty())
cout << "null";uhmm, what about the;
char temp[100];how would compare to null...
btw, thank you...:D
Given char temp[100]; I guess you must be talking of how to determine is a string is empty. How about something like if(strlen(temp) == 0) { } .
Does it work in C++ like this?:
if( *temp_ptr == 0 ) {}its not working, i just press enter but it does not alert me that i placed nothing... T_T
>i just want to know how to compare a string to null
You don't. NULL is a null pointer and a string object isn't a pointer. Most likely you want to check for an empty string:
if ( x == "" )or
if ( x.empty() )And such.
>this is what my mentor told me to do...
Your mentor probably thought you were using C-style strings simulated with pointers. Your sample code isn't though, so that advice is useless.
>string class has no overloaded "==" operator.
Yes, it does. That's one of the selling points of the class.
>i just press enter but it does not alert me that i placed nothing...
Post your full program. We don't like playing 20 questions.
> i just press enter but it does not alert me that i placed nothing.
Maybe the newline is getting the best of you...
In c++ you can compare a "null string" by going (x != npos) Cant you?
There is no 'null string' as such, only null pointers. A string instance can't be null because it has just been instantiated. And x != string::npos doesn't make sense either, one is a string object while the other is most probably an unsigned integer.
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