We are given:
\[
\int \frac{\sin x + \cos x}{\sin x - \cos x} \, dx
\]
Let us use substitution. Let:
\[
u = \sin x - \cos x \Rightarrow \frac{du}{dx} = \cos x + \sin x
\]
So,
\[
\frac{\sin x + \cos x}{\sin x - \cos x} \, dx = \frac{du}{u}
\]
Now integrate:
\[
\int \frac{du}{u} = \log|u| + c = \log|\sin x - \cos x| + c
\]
Hence,
\[
\int \frac{\sin x + \cos x}{\sin x - \cos x} \, dx = \boxed{\log|\cos x - \sin x| + c}
\]