Compare string from the user [duplicate]

Question

I am trying to delete a node from the linked list. Node has a name that user enters. But I couldn't figure out how can I ignore the uppercase/lowercase in while loop. Here is my code.

void del(string e) { temp=new node; temp=head; temp2=new node; temp2=temp->next; if(temp->info==e) { head=temp->next; delete temp; } else { while(temp2->info!=e) { temp=temp->next; temp2=temp2->next; } temp2=temp2->next; temp->next=temp2; } }

And I get the string by this

cout<<"Enter the name to delete"<<endl; ws(cin); getline(cin,e); del(e);

So is there any way to ignore uppercase/lowercase in while loop and if statement?

"how can I ignore the case" - you mean ignore letter cases? — Fureeish
– Fureeish, Commented Dec 20, 2017 at 15:10
Transform both strings to lowercase or uppercase and compare. — Ron
– Ron, Commented Dec 20, 2017 at 15:19

Serge · Accepted Answer · 2017-12-20 15:25:30Z

The trick to non-cases sensitive comparison of two strings is to convert both of them either to lower or to upper case and then compare.

Unfortunately stl does not provide a very convenient way for the case conversions. So, here are some possibilities: https://stackoverflow.com/a/313990/1143850. just copying from there:

#include <algorithm> #include <string> std::string data = "Abc"; std::transform(data.begin(), data.end(), data.begin(), ::tolower);

so, in your case,

 string lowerE = std::transform(e.begin(), e.end(), e.begin(), ::tolower); ... while(std::transform(temp2->info.begin(), temp2->info.end(), temp2->info.begin(), ::tolower) != lowerE) ...

Of course, you can create a function to simplfy it or use a different method of conversion there.

and another possibility definitely is to create you own comparison function and compare char by char, using the tolower or towlower function.

PspSetProcessPpmPolicy · Accepted Answer · 2017-12-20 15:41:02Z

You don't need to manually convert the case of the strings being converted. If you're dealing with strings, use strcmp. For case insensitive checks, you can use _strcmpi.

E.g.

if(!strcmp(String1, String2)) { .... }

If strcmp returns 0 (FALSE) then there was a match, with case sensitivity applied.

For comparisons without case sensitivity, you use _strcmpi.

E.g.

#include <Windows.h> #include <iostream> using namespace std; BOOL StringMatch( CONST CHAR *CmpString, CONST CHAR *CmpString2 ) { return (!_strcmpi(CmpString, CmpString2)) ? TRUE : FALSE; } int main() { if (StringMatch("hello", "HELLO")) { cout << "Match without case sensitivity\n"; } getchar(); return 0; }

Since you're using std::string, you can use the .c_str().

E.g.

string hellostring = "hello"; if (StringMatch(hellostring.c_str(), "HELLO")) { cout << "Match without case sensitivity\n"; }

If you ever need to switch to Unicode encoding instead of Ascii, you have wcscmp and _wcs*/wcs*.

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