\documentclass[compress,red]{beamer}
\mode<presentation>\begin{document}
% 使用verbatim前面必須加fragile
\begin{frame}[fragile]\frametitle{An Algorithm For Finding Primes Numbers.}
\begin{verbatim}
int main (void)
{
std::vector<bool> is_prime (100, true);
for (int i = 2; i < 100; i++)
if (is_prime[i])
{
std::cout << i << " ";
for (int j = i; j < 100; is_prime [j] = false, j+=i);
}
return 0;
}
\end{verbatim}
\begin{uncoverenv}<2>Note the use of \verb|std::|.
\end{uncoverenv}
\end{frame}
\end{document}