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    <p><strong>Edit</strong> -- warning: the following works only for this <em>specific</em> case, <strong>not</strong> for the general case -- see below.</p> <pre><code>int value = 0; d.TryGetValue(p, out value); d[p] = value + 1; </code></pre> <p>this is equivalent to the following Python snippet (which is better than the one you show):</p> <pre><code>d[p] = d.get(p, 0) + 1 </code></pre> <p><code>setdefault</code> is like <code>get</code> (fetch if present, else use some other value) plus the side effect of injecting the key / other value pair in the dict if the key wasn't present there; but here this side effect is useless, since you're about to assign <code>d[p]</code> anyway, so using <code>setdefault</code> in this case is just goofy (complicates things and slow you down to no good purpose).</p> <p>In C#, <code>TryGetValue</code>, as the name suggests, tries to get the value corresponding to the key into its <code>out</code> parameter, but, if the key's not present, then it (<strong>warning: the following phrase is <em>not</em> correct:</strong>) just leaves said value alone (<strong>edit:</strong>) What it actually does if the key's not present is <em>not</em> to "leave the value alone" (it can't, since it's an <code>out</code> value; see the comments), but rather to set it to the default value for the type -- here, since 0 (the default value) is what we want, we're fine, but this doesn't make <code>TryGetValue</code> a general-purpose substitute for Python's <code>dict.get</code>.</p> <p><code>TryGetValue</code> also returns a boolean result, telling you whether it did manage to get the value or not, but you don't need it in this case (just because the default behavior happens to suit us). To build the general equivalent of Python's <code>dict.get</code>, you need another idiom:</p> <pre><code>if (!TryGetValue(d, k)) { k = whatyouwant; } </code></pre> <p>Now <em>this</em> idiom is indeed the general-purpose equivalent to Python's <code>k = d.get(k, whatyouwant)</code>.</p>
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    1. POC#: Does a dictionary in C# have something similar to the Python setdefault?
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    1. COAlex, I think I got burned by this, I had made the same assumption about TryGetValue in the event of the value's absence, that the out value would be unchanged. BUT, the docs say that the out value get set with the default value of the value's type. Try initializing value in your example to 100, and in the absence of p in d, value will have the value of 0 after calling TryGetValue. I tripped over this by trying to look for override settings in a dictionary, and found that I was resetting all of my values to 0 if no override existed.
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    2. COTo expand on Paul's comment, in C#, the callee (in this case TryGetValue) MUST write to the out parameter before returning -- and is not allowed to read from the out-parameter before writing to it. So TryGetValue couldn't leave the value alone even if it wanted to: it has to write to it, and it can't write the passed-in value because it can't read the passed-in value. (If TryGetValue took a ref parameter, that would be a different matter.)
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    3. COThanks -- this is an important error on my part so I'm going to edit the answer to clarify it!
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