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POC strings vs const char* is confusing me... help please
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  1. POC strings vs const char* is confusing me... help please
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    copied!<p>I'm a C/C++ beginner trying to build what seems like a pretty simple program: it loads a file into a c-string (const char*). However, although the program is incredibly simple, it's not working in a way I understand. Take a look:</p> <pre><code>#include &lt;iostream&gt; #include &lt;fstream&gt; std::string loadStringFromFile(const char* file) { std::ifstream shader_file(file, std::ifstream::in); std::string str((std::istreambuf_iterator&lt;char&gt;(shader_file)), std::istreambuf_iterator&lt;char&gt;()); return str; } const char* loadCStringFromFile(const char* file) { std::ifstream shader_file(file, std::ifstream::in); std::string str((std::istreambuf_iterator&lt;char&gt;(shader_file)), std::istreambuf_iterator&lt;char&gt;()); return str.c_str(); } int main() { std::string hello = loadStringFromFile("hello.txt"); std::cout &lt;&lt; "hello: " &lt;&lt; hello.c_str() &lt;&lt; std::endl; const char* hello2 = loadCStringFromFile("hello.txt"); std::cout &lt;&lt; "hello2: " &lt;&lt; hello2 &lt;&lt; std::endl; hello2 = hello.c_str(); std::cout &lt;&lt; "hello2 = hello.c_str(), hello2: " &lt;&lt; hello2 &lt;&lt; std::endl; return 0; } </code></pre> <p>The output looks like this:</p> <pre><code>hello: Heeeeyyyyyy hello2: 青! hello2 = hello, hello2: Heeeeyyyyyy </code></pre> <p>The initial hello2 value changes every time, always some random kanji (I'm using a Japanese computer, so I'm guessing that's why it's kanji).</p> <p>In my naive view, it seems like the two values should print identically. One function returns a c++ string, which I then convert to a c-string, and the other loads the string, converts the c-string from that and returns it. I made sure that the string was loading properly in loadCStringFromFile by couting the value before I returned it, and indeed it was what I had thought, e.g.:</p> <pre><code>/*(inside loadCStringFromFile)*/ const char* result = str.c_str(); std::cout &lt;&lt; result &lt;&lt; std::endl;//prints out "Heeeyyyyyy" as expected return result; </code></pre> <p>So why should the value change? Thanks for the help...</p>
 

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