How do I add Markdown formatting in a code / pre block?

This syntax should solve your problem :

    ```
    int main(void) {
       **return 0;**
    }
    ```

Just type three backticks in the beginning of the code block and it's should work.

You would have to do this in HTML, by design.

However, inside Markdown code spans and blocks, angle brackets and ampersands are always encoded automatically.

<pre>
int main(void) {
    <b>return 0;</b>
}
</pre>

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