Another testsuite patch and a bug in string.find

[Anthony Williams]

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Here is a patch to testsuite/21_strings/find.cc, which I think makes
it more standard compliant.

The patch relates to empty strings. An empty string object contains
no characters, so I believe that it should be found at all positions,
and the following code should produce the given output. This
highlights a bug in string.find, since libstdc++ produces the second
set of output.

include <iostream>
#include <string>
 
int main()
{
    std::string a("hello");
    std::string b;
 
    for(unsigned i=0;i<=a.size();++i)
        std::cout<<a.find(b,i)<<std::endl;
}
 
Expected output:
0
1
2
3
4
4294967295
 
libstdc++-v3 output:
5
5
5
5
5
5

Anthony

testsuite/21_strings/find.cc: Empty strings can be found at all
positions

Index: find.cc
===================================================================
RCS file: /cvs/gcc/egcs/libstdc++-v3/testsuite/21_strings/find.cc,v
retrieving revision 1.1
diff -u -p -r1.1 find.cc
- --- find.cc     2000/04/21 20:33:33     1.1
+++ find.cc     2000/06/07 10:36:09
@@ -56,21 +56,22 @@ bool test01(void)
   test &= csz01 == 8;
   csz01 = str01.find(str03, 12);
   test &= csz01 == npos;
- -  // It is implementation-defined if a given string contains an
empty
- -  // string. The only two times a char_type() (== empty string)
ending
- -  // element is required to be part of the string is on c_str() and
- -  // operator[size()] const: the indeterminate, stored state of the
- -  // string can vary, and not include a terminal char_type().
+
+  // An empty string consists of no characters
+  // therefore it should be found at every point in a string,
+  // except beyond the end
   csz01 = str01.find(str04, 0);
- -  test &= csz01 == npos || csz01 == str01.size();
+  test &= csz01 == 0; 
   csz01 = str01.find(str04, 5);
- -  test &= csz01 == npos || csz01 == str01.size();
+  test &= csz01 == 5; 
+  csz01 = str01.find(str04, str01.size());
+  test &= csz01 == npos; 
   
   // size_type find(const char* s, size_type pos, size_type n)
const;
   csz01 = str01.find(str_lit01, 0, 3);
   test &= csz01 == 0;
   csz01 = str01.find(str_lit01, 3, 0);
- -  test &= csz01 == npos;
+  test &= csz01 == 3; // zero length string should be found at pos
 
   // size_type find(const char* s, size_type pos = 0) const;
   csz01 = str01.find(str_lit01);
@@ -107,15 +108,15 @@ bool test01(void)
   csz01 = str01.find_first_of(str05, 4);
   test &= csz01 == 4;
 
- -  // It is implementation-defined if a given string contains an
empty
- -  // string. The only two times a char_type() (== empty string)
ending
- -  // element is required to be part of the string is on c_str() and
- -  // operator[size()] const: the indeterminate, stored state of the
- -  // string can vary, and not include a terminal char_type().
+  // An empty string consists of no characters
+  // therefore it should be found at every point in a string,
+  // except beyond the end
+  // However, str1.find_first_of(str2,pos) finds the first character
in 
+  // str1 (starting at pos) that exists in str2, which is none for
empty str2
   csz01 = str01.find_first_of(str04, 0);
- -  test &= csz01 == npos || csz01 == str01.size();
+  test &= csz01 == npos; 
   csz01 = str01.find_first_of(str04, 5);
- -  test &= csz01 == npos || csz01 == str01.size();
+  test &= csz01 == npos; 
   
   // size_type find_first_of(const char* s, size_type pos, size_type
n) const;
   csz01 = str01.find_first_of(str_lit01, 0, 3);

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