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Hi,

I want to compare two strings regardless of the lowercase or uppercase.
For example, "txt" same as "TXT", "Txt", ...

I know that there's stricmp in some c++ that can perform a lowercase
comparison. But when I use <cstring>, I can't find such function. Do you
know any other standard c++ function(s) can do this task?

Thanks,
X

xuatla wrote:
> Hi,
>
> I want to compare two strings regardless of the lowercase or uppercase.
> For example, "txt" same as "TXT", "Txt", ...
>
> I know that there's stricmp in some c++ that can perform a lowercase
> comparison. But when I use <cstring>, I can't find such function. Do you
> know any other standard c++ function(s) can do this task?
>
> Thanks,
> X

I think you have to roll your own.

how about using c_str() first and then using strcmp?
http://www.cppreference.com/cppstring/c_str.html

i quickly wrote something to test this myelf (hopefully this is the
correct way to do this):

#include <iostream>
#include <string>

using namespace std;

int main()
{
string test1 = "abcd";
string test2 = "AbCd";

cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
test2.c_str()) << endl;

test2 = "ABCD";

cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
test2.c_str()) << endl;

test2 = "abcd";


cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
test2.c_str()) << endl;

test2 = "dcba";

cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
test2.c_str()) << endl;

test2 = "abcdE";

cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
test2.c_str()) << endl;

return 0;
}

output
----------------------
abcd AbCd 1
abcd ABCD 1
abcd abcd 0
abcd dcba -1
abcd abcdE -1

xuatla wrote:

> Hi,
>
> I want to compare two strings regardless of the lowercase or uppercase.
> For example, "txt" same as "TXT", "Txt", ...
>
> I know that there's stricmp in some c++ that can perform a lowercase
> comparison. But when I use <cstring>, I can't find such function. Do you
> know any other standard c++ function(s) can do this task?
>
> Thanks,
> X

Such comparisons depend on your locale. The following code defaults to the
global locale std::locale().

#include <locale>
#include <string>
#include <iostream>

template < typename CharIter >
bool
sequence_equal_to_ignoring_case ( CharIter a_from, CharIter a_to,
CharIter b_from, CharIter b_to,
std::locale const & loc = std::locale() ) {
if ( std::distance( a_from, a_to )
!=
std::distance( b_from, b_to ) ) {
return ( false );
}
for ( CharIter a_iter = a_from, b_iter = b_from;
a_iter != a_to;
++ a_iter, ++b_iter ) {
if ( std::tolower( *a_iter, loc ) != std::tolower( *b_iter, loc ) ) {
return ( false );
}
}
return ( true );
}

bool
string_equal_to_ignoring_case ( std::string const & a,
std::string const & b,
std::locale const & loc = std::locale() ) {
return( sequence_equal_to_ignoring_case( a.begin(), a.end(),
b.begin(), b.end(),
loc ) );
}

int main ( void ) {
std::string a ( "Hello World!" );
std::string b ( "hello world!" );
std::cout << string_equal_to_ignoring_case( a, b ) << '\n';
}


Best

Kai-Uwe Bux

ps.: Isn't this in the FAQ? and should it be in the FAQ?

Thank you.

Yes for functions related with char * I use .c_str().
But strcmp is case sensative.

For example, comparing abcd AbCC also gives result 1. So this function
is not good for case insensative comparison.

I am also looking for "standard" functions as makeupper() or makelower()
in CString in MFC. It seems that we don't have such functions in
standard C++ library.

Regards,
X


wrote:
> how about using c_str() first and then using strcmp?
> http://www.cppreference.com/cppstring/c_str.html
>
> i quickly wrote something to test this myelf (hopefully this is the
> correct way to do this):
>
> #include <iostream>
> #include <string>
>
> using namespace std;
>
> int main()
> {
> string test1 = "abcd";
> string test2 = "AbCd";
>
> cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
> test2.c_str()) << endl;
>
> test2 = "ABCD";
>
> cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
> test2.c_str()) << endl;
>
> test2 = "abcd";
>
>
> cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
> test2.c_str()) << endl;
>
> test2 = "dcba";
>
> cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
> test2.c_str()) << endl;
>
> test2 = "abcdE";
>
> cout << test1 << " " << test2 << " " << strcmp(test1.c_str(),
> test2.c_str()) << endl;
>
> return 0;
> }
>
> output
> ----------------------
> abcd AbCd 1
> abcd ABCD 1
> abcd abcd 0
> abcd dcba -1
> abcd abcdE -1
>

Thank you very much!! This works well for me.

Regards,
X


Kai-Uwe Bux wrote:
> xuatla wrote:
>
>
>>Hi,
>>
>>I want to compare two strings regardless of the lowercase or uppercase.
>>For example, "txt" same as "TXT", "Txt", ...
>>
>>I know that there's stricmp in some c++ that can perform a lowercase
>>comparison. But when I use <cstring>, I can't find such function. Do you
>>know any other standard c++ function(s) can do this task?
>>
>>Thanks,
>>X
>
>
> Such comparisons depend on your locale. The following code defaults to the
> global locale std::locale().
>
> #include <locale>
> #include <string>
> #include <iostream>
>
> template < typename CharIter >
> bool
> sequence_equal_to_ignoring_case ( CharIter a_from, CharIter a_to,
> CharIter b_from, CharIter b_to,
> std::locale const & loc = std::locale() ) {
> if ( std::distance( a_from, a_to )
> !=
> std::distance( b_from, b_to ) ) {
> return ( false );
> }
> for ( CharIter a_iter = a_from, b_iter = b_from;
> a_iter != a_to;
> ++ a_iter, ++b_iter ) {
> if ( std::tolower( *a_iter, loc ) != std::tolower( *b_iter, loc ) ) {
> return ( false );
> }
> }
> return ( true );
> }
>
> bool
> string_equal_to_ignoring_case ( std::string const & a,
> std::string const & b,
> std::locale const & loc = std::locale() ) {
> return( sequence_equal_to_ignoring_case( a.begin(), a.end(),
> b.begin(), b.end(),
> loc ) );
> }
>
> int main ( void ) {
> std::string a ( "Hello World!" );
> std::string b ( "hello world!" );
> std::cout << string_equal_to_ignoring_case( a, b ) << '\n';
> }
>
>
> Best
>
> Kai-Uwe Bux
>
> ps.: Isn't this in the FAQ? and should it be in the FAQ?

Kai-Uwe Bux wrote:
> Such comparisons depend on your locale. The following code defaults to the
> global locale std::locale().
>
> #include <locale>
> #include <string>
> #include <iostream>
>
> template < typename CharIter >
> bool
> sequence_equal_to_ignoring_case ( CharIter a_from, CharIter a_to,
> CharIter b_from, CharIter b_to,
> std::locale const & loc = std::locale() ) {
> if ( std::distance( a_from, a_to )
> !=
> std::distance( b_from, b_to ) ) {
> return ( false );
> }
> for ( CharIter a_iter = a_from, b_iter = b_from;
> a_iter != a_to;
> ++ a_iter, ++b_iter ) {
> if ( std::tolower( *a_iter, loc ) != std::tolower( *b_iter, loc ) ) {
> return ( false );
> }
> }
> return ( true );
> }
>
> bool
> string_equal_to_ignoring_case ( std::string const & a,
> std::string const & b,
> std::locale const & loc = std::locale() ) {
> return( sequence_equal_to_ignoring_case( a.begin(), a.end(),
> b.begin(), b.end(),
> loc ) );
> }
>
> int main ( void ) {
> std::string a ( "Hello World!" );
> std::string b ( "hello world!" );
> std::cout << string_equal_to_ignoring_case( a, b ) << '\n';
> }

Any problems with this solution ??


bool
char_equal_icase(char a, char b, std::locale const & loc = std::locale() )
{
return ( std::tolower( a, loc ) ==
std::tolower( b, loc ) );
}

bool
string_equal_icase ( std::string const & a,
std::string const & b,
std::locale const & loc = std::locale() )
{
return ((a.size() == b.size()) &&
(std::mismatch(a.begin(), a.end(), b.begin(), char_equal_icase).first == a.end()));
}


Stefan

Stefan Näwe wrote:
> Any problems with this solution ??

Yes!
The locale doesn'T get passed to char_equal_icase().

> bool
> char_equal_icase(char a, char b, std::locale const & loc = std::locale() )
> {
> return ( std::tolower( a, loc ) ==
> std::tolower( b, loc ) );
> }
>
> bool
> string_equal_icase ( std::string const & a,
> std::string const & b,
> std::locale const & loc = std::locale() )
> {
> return ((a.size() == b.size()) &&
> (std::mismatch(a.begin(), a.end(), b.begin(), char_equal_icase).first == a.end()));
> }

Better:


struct char_equal_icase
{
char_equal_icase(std::locale const & loc = std::locale())
: loc_(loc)
{
}

bool
operator()(char a, char b )
{
return ( std::tolower( a, loc_ ) == std::tolower( b, loc_) );
}

private:
std::locale const & loc_;
};

bool
string_equal_icase ( std::string const & a,
std::string const & b,
std::locale const & loc = std::locale() )
{
return ((a.size() == b.size()) &&
(std::mismatch(a.begin(), a.end(), b.begin(), char_equal_icase(loc)).first == a.end()));
}



Stefan

xuatla wrote:
> Hi,
>
> I want to compare two strings regardless of the lowercase or uppercase.
> For example, "txt" same as "TXT", "Txt", ...
>
> I know that there's stricmp in some c++ that can perform a lowercase
> comparison. But when I use <cstring>, I can't find such function. Do you
> know any other standard c++ function(s) can do this task?

There is none.

You can use Apache Portable Runtime for that:
http://apr.apache.org/docs/apr/group...rings.html#ga1

Maxim Yegorushkin wrote:
> xuatla wrote:
>
>>Hi,
>>
>>I want to compare two strings regardless of the lowercase or uppercase.
>>For example, "txt" same as "TXT", "Txt", ...
>>
>>I know that there's stricmp in some c++ that can perform a lowercase
>>comparison. But when I use <cstring>, I can't find such function. Do you
>>know any other standard c++ function(s) can do this task?
>
>
> There is none.
>
> You can use Apache Portable Runtime for that:
> http://apr.apache.org/docs/apr/group...rings.html#ga1
>

Thank you.

I got from another group that
int strcasecmp((const char *s1, const char *s2)
works for case nonsensative comparison.

It exists in my c++ 3.3.3 but not in visual c++. So I think this might
not be a standard c++ function.

I have solved this problem. Thanks to all.

X