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POReplace in string iteration (out_of_range)
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  1. POReplace in string iteration (out_of_range)
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    copied!<p>I wrote a function which percent-encodes a string, as follows:</p> <pre><code>string percent_encode(string str) { string reserved = // gen-delims ":/?#[]@" // sub-delims "!$&amp;'()*+,;=" ; for(string::iterator i = str.begin(); i &lt; str.end(); i++) { int c = *i; // replaces reserved, unreserved non-ascii and space characters. if(c &gt; 127 || c == 32 || reserved.find(*i) != string::npos) { std::stringstream ss; ss &lt;&lt; std::hex &lt;&lt; c; str.replace(i, i + 1, "%" + ss.str()); } } return str; } </code></pre> <p>When I call this function for a string like "a&amp;b", an out_of_range exception is thrown:</p> <pre><code>terminate called after throwing an instance of 'std::out_of_range' what(): basic_string::replace </code></pre> <p>I traced this exception with a debugger and saw, that the replacing worked well, but it iterates somehow beyond end();</p> <p>This is what I get, when I watch the iterator "i":</p> <pre><code>{_M_current = 0x7fc43d61bd78 "a&amp;b"} {_M_current = 0x7fc43d61bd79 "&amp;b"} {_M_current = 0x7fc43d61bd7a "b"} {_M_current = 0x7fc43d61bd7b ""} {_M_current = 0x7fc43d61bd7c "o = a&amp;b\n"} {_M_current = 0x7fc43d61bd7d " = a&amp;b\n"} </code></pre> <p>Then it tries to replace "=" and fails with an out_of_range exception. I do not understand, how it is possible for the iterator to get obviously beyond end().</p> <p>I would be appreciated, if someone could explain me, how this is possible, because I could not find someone in the web, who had the same problem.</p> <p>Thanks and regards,</p> <p>reeaal</p> <p>Edit:</p> <p>Argh, I really thought to complicated. x) This is how I solved it now. </p> <pre><code>string percent_encode(string str) { string reserved = // gen-delims ":/?#[]@" // sub-delims "!$&amp;'()*+,;=" ; std::stringstream ss; for(string::iterator i = str.begin(); i &lt; str.end(); i++) { // encodes reserved, unreserved non-ascii and space characters. int c = *i; if(c &gt; 126 || c == 32 || reserved.find(*i) != string::npos) { ss &lt;&lt; '%' &lt;&lt; std::hex &lt;&lt; c; } else { ss &lt;&lt; *i; } } return ss.str(); } </code></pre> <p>Thanks Diego :)</p>
 

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