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<TITLE>Example Program: Exceptions</TITLE>
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<H2>18.4 Example Program: Exceptions</H2>
<BLOCKQUOTE><HR><B>
NOTE -- This program is in the file <code>tutorial/stdexcept.cpp</code>.
</B><HR></BLOCKQUOTE>
<A NAME="idx428"><!></A>
<P>This following example program demonstrates the use of exceptions:</P>

<UL><PRE>
#include &lt;string&gt;      // for string
#include &lt;stdexcept&gt;   // for exception, runtime_error, out_of_range
#include &lt;iostream&gt;    // for cout


int main ()
{
    // First we'll incite and catch an exception from the C++ Standard
    // library class std::string by attempting to replace a substring
    // starting at a position beyond the end of the string object.
    try {
        std::string ().replace (100, 1, 1, 'c');
    }
    catch (std::out_of_range &amp;e) {

        // Print out the exception string, which in this implementation
        // includes the location and the name of the function that threw
        // the exception along with the reason for the exception.
        std::cout &lt;&lt; "Caught an out_of_range exception: "
                  &lt;&lt; e.what () &lt;&lt; '\n';
    }
    catch (std::exception &amp;e) {

        std::cout &lt;&lt; "Caught an exception of an unexpected type: "
                  &lt;&lt; e.what () &lt;&lt; '\n';
    }
    catch (...) {
        std::cout &lt;&lt; "Caught an unknown exception\n";
    }
    
    // Throw another exception.
    try {
        throw std::runtime_error ("a runtime error");
    }
    catch (std::runtime_error &amp;e) {
        std::cout &lt;&lt; "Caught a runtime_error exception: "
                  &lt;&lt; e.what () &lt;&lt; '\n';
    }
    catch (std::exception &amp;e) {
        std::cout &lt;&lt; "Caught an exception of an unexpected type: "
                  &lt;&lt; e.what () &lt;&lt; '\n';
    } 
    catch (...) {
        std::cout &lt;&lt; "Caught an unknown exception\n";
    }
   
    return 0;
}
</PRE></UL>
<P>The exact output of the program is specific to the compiler used to compile it and to the location of the library headers but may look something like this:</P><UL><PRE>
Caught an out_of_range exception: /usr/local/stdcxx/include/string.cc:422: std::string& std::string::replace(size_type, size_type, size_type, char_type): argument value 100 out of range [0, 0)
Caught a runtime_error exception: a runtime error
</UL></PRE>

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