C++ custom string trim implementation valgrind warning -

recently implemented custom function trimming std::strings removes whitespace character prefixes , suffixes.

i tested functionality , works according unit tests, when run tests using valgrind, following output:

==4486== conditional jump or move depends on uninitialised value(s) ==4486==    @ 0x415dda: is_ws_char(char) (parse.cpp:22) ==4486==    0x415bc6: parse::trim(std::string&) (parse.cpp:34) 

my input test string was

string s("  a"); 

i not see problem here. code looks this:

inline bool is_ws_char(const char c) {    // line 22 in code   return (c == ' ' || c == '\n' || c == '\t' || c == '\r'); }   void parse::trim(std::string& str) {   size_t len = str.size();   size_t = 0;   (; < len; ++i)     if (!is_ws_char(str[i]))       break;   const size_t start = i;   (i = len - 1; >= 0; --i)     if (!is_ws_char(str[i]))              // line 34 in code       break;   const size_t end = i;   str = str.substr(start, end - start + 1); } 

does has idea problem here? briefly thought is's valgrind oddity, seems rather unlikely.

thanks in advance!

this loop invalid

for (i = len - 1; >= 0; --i) 

the condition equal true because expression --i >= 0 due fact unsigned integer.

also when str.size() equal 0 len - 1 equal std::string::npos.