Insert variable into string
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Hello experts, which advantages does one of these two methods
return (string.Format("Device #{0}", devNr));
return ("Device #" + devNr.ToString());have over the other one? They seem to produce identical results.
Ciao, luker
They produce identical results. The first one is consider better because it uses less memory. The second version allocates memory for 3 strings ("Device #", result of devNr.ToString() and result of entire statement), which makes application consume more memory. The first one isn't (to my knowledge) creating such an overhead. If you need to use second form it's better to use StringBuilder class. And personally I consider first form more readable.
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They produce identical results. The first one is consider better because it uses less memory. The second version allocates memory for 3 strings ("Device #", result of devNr.ToString() and result of entire statement), which makes application consume more memory. The first one isn't (to my knowledge) creating such an overhead. If you need to use second form it's better to use StringBuilder class. And personally I consider first form more readable.
lukasz_nowakowski wrote:
And personally I consider first form more readable.
I agree, String.Format is more readable, especially when you have a few more arguments.
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They produce identical results. The first one is consider better because it uses less memory. The second version allocates memory for 3 strings ("Device #", result of devNr.ToString() and result of entire statement), which makes application consume more memory. The first one isn't (to my knowledge) creating such an overhead. If you need to use second form it's better to use StringBuilder class. And personally I consider first form more readable.
I totally agree the 1st form is better, just on readability alone. I'd question your point about the
StringBuilderas a replacement for the second form, creating an instance of this type has some overhead, for small concatenations the string builder is worse than the code supplied in the OP, but it has become received wisdom thatStringBuilderis more efficient. I posted a link a while back http://www.yoda.arachsys.com/csharp/stringbuilder.html[^] to an archive of stuff John Skeet has written about c# amongst others. He has tested the received wisdom, and found it wanting, the section "So I Should Use StringBuilder Everywhere, Right?" is really the nub of the problem. It's worth doing the test he suggests, for "small" concats the overhead of theStringBuilderoutweighs the benefits (and dirties the code). For multiple concats (e.g. in a loop)StringBuilder `is _much_ more efficient. **Dalek Dave:** There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter. **Pete o'Hanlon:** If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.` -
They produce identical results. The first one is consider better because it uses less memory. The second version allocates memory for 3 strings ("Device #", result of devNr.ToString() and result of entire statement), which makes application consume more memory. The first one isn't (to my knowledge) creating such an overhead. If you need to use second form it's better to use StringBuilder class. And personally I consider first form more readable.
Not to mention that the first form makes localization easier between english and any of {French, Spanish, Italian, etc..}
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They produce identical results. The first one is consider better because it uses less memory. The second version allocates memory for 3 strings ("Device #", result of devNr.ToString() and result of entire statement), which makes application consume more memory. The first one isn't (to my knowledge) creating such an overhead. If you need to use second form it's better to use StringBuilder class. And personally I consider first form more readable.
I'm just curious about something here. The header for String.Format looks like:
string Format(string strInput, object objInput)
right? So, right away, a new string is created, along with a reference to the object. Now, the code, would have to first find the starting and ending brace and pull out the formatting codes. Then, it would have to take the object and apply the formatting code to it and then return the part of the string before the brace, the formatted code, and the part of the string after the brace. In other words, if you had passed it "format {0} me", the return would look like:
return left(strInput, startingBraceIndex) & Format(objInput, formatCode) & right(strInput, strInput.Length - endingBraceIndex - 1)
or something like that. Of course, it is (hopefully) optimized a bit, so that it's not creating as many copies, but still, wouldn't more memory have to be used for the Format method, plus more processing cycles because or what all has to be done...whereas the second routine is much more straightforward. As far as performance, I just don't see how the first is more efficient than the second. I also don't see how the first is more readable...even with more parameters, you would have to know what was in each spot in the array, so as far as readability, the second would be more readable as well. Is
object[] objArray = {devNr, idNr, testNr};
return string.Format("Device #{0}, ID#{1}, Test#{2}", objArry);really more readable than:
return "Device #" + devNr + ", ID#" + idNr + ", Test#" + testNr
? Sure the first one is a bit cleaner, but IMO, it's not more readable. Besides, whatever happened to Occam's Razor?
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I'm just curious about something here. The header for String.Format looks like:
string Format(string strInput, object objInput)
right? So, right away, a new string is created, along with a reference to the object. Now, the code, would have to first find the starting and ending brace and pull out the formatting codes. Then, it would have to take the object and apply the formatting code to it and then return the part of the string before the brace, the formatted code, and the part of the string after the brace. In other words, if you had passed it "format {0} me", the return would look like:
return left(strInput, startingBraceIndex) & Format(objInput, formatCode) & right(strInput, strInput.Length - endingBraceIndex - 1)
or something like that. Of course, it is (hopefully) optimized a bit, so that it's not creating as many copies, but still, wouldn't more memory have to be used for the Format method, plus more processing cycles because or what all has to be done...whereas the second routine is much more straightforward. As far as performance, I just don't see how the first is more efficient than the second. I also don't see how the first is more readable...even with more parameters, you would have to know what was in each spot in the array, so as far as readability, the second would be more readable as well. Is
object[] objArray = {devNr, idNr, testNr};
return string.Format("Device #{0}, ID#{1}, Test#{2}", objArry);really more readable than:
return "Device #" + devNr + ", ID#" + idNr + ", Test#" + testNr
? Sure the first one is a bit cleaner, but IMO, it's not more readable. Besides, whatever happened to Occam's Razor?
Interesting point... I was curious, so I checked String.Format with .NET Reflector... Actually it doesn't split string. Under the hood it uses StringBuilder.AppendFormat. Method is quite long and operates on char[] (from format.ToCharArray()). And I'm tired, so didn't trace the method body. Just took a look on it.
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I totally agree the 1st form is better, just on readability alone. I'd question your point about the
StringBuilderas a replacement for the second form, creating an instance of this type has some overhead, for small concatenations the string builder is worse than the code supplied in the OP, but it has become received wisdom thatStringBuilderis more efficient. I posted a link a while back http://www.yoda.arachsys.com/csharp/stringbuilder.html[^] to an archive of stuff John Skeet has written about c# amongst others. He has tested the received wisdom, and found it wanting, the section "So I Should Use StringBuilder Everywhere, Right?" is really the nub of the problem. It's worth doing the test he suggests, for "small" concats the overhead of theStringBuilderoutweighs the benefits (and dirties the code). For multiple concats (e.g. in a loop)StringBuilder `is _much_ more efficient. **Dalek Dave:** There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter. **Pete o'Hanlon:** If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.`Interestingly, the String.Format uses a StringBuilder...
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Interestingly, the String.Format uses a StringBuilder...
I'm not convinced
String.Formatis more efficient than the straight concat, but I do think the format route is clearer. Disassembling String.Format gives this line:StringBuilder builder = new StringBuilder(format.Length + (args.Length * 8));
So it is likely that, as long as the argument passed average 8 characters or less, the
StringBuilderwill probably be more efficient at first glance. Of course, I haven't tested this, but it would be easy to rig a test to find out. The point I was trying to make was that the assumption thatStringBuilderis always more efficient than direct string manipulation is demonstrably false. Additionally, I'd say, unless the code is a block you know will be heavily repeated, early optimisation will ruin otherwise clear code without real benefit. I personally would only consider using aStringBuilderwhen I know this is the case, or testing reveals poor performance, or the system must perform with the highest possible efficiency for some reason(e.g. real time). This is in line with the KSS and YAGNI principles.Dalek Dave: There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter. Pete o'Hanlon: If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.
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I'm not convinced
String.Formatis more efficient than the straight concat, but I do think the format route is clearer. Disassembling String.Format gives this line:StringBuilder builder = new StringBuilder(format.Length + (args.Length * 8));
So it is likely that, as long as the argument passed average 8 characters or less, the
StringBuilderwill probably be more efficient at first glance. Of course, I haven't tested this, but it would be easy to rig a test to find out. The point I was trying to make was that the assumption thatStringBuilderis always more efficient than direct string manipulation is demonstrably false. Additionally, I'd say, unless the code is a block you know will be heavily repeated, early optimisation will ruin otherwise clear code without real benefit. I personally would only consider using aStringBuilderwhen I know this is the case, or testing reveals poor performance, or the system must perform with the highest possible efficiency for some reason(e.g. real time). This is in line with the KSS and YAGNI principles.Dalek Dave: There are many words that some find offensive, Homosexuality, Alcoholism, Religion, Visual Basic, Manchester United, Butter. Pete o'Hanlon: If it wasn't insulting tools, I'd say you were dumber than a bag of spanners.
I wasn't arguing for StringBuilder. I was just noting that you were saying for smaller concats, StringBuilder won't be more efficient. You were saying you preferred format 1 (albeit for readability) and I was just pointing out that format 1 used a StringBuilder which you were seeming to argue against. I was just pointing out the irony is all. For what he wrote, I would always lean towards the second format. Especially now that I've seen the path String.Format(String, Object) takes:
String.Format(String, Object)callsString.Format(IFormatProvider, String, Object[])callsStringBuilder(int capacity) andStringBuilder.AppendFormat(IFormatProvider, string format, params object[] args)andStringBuilder.ToString()which callsstring.FastAllocateString(int length)then concatenates each of the StringBuilder parts. It's way more code being run. -
Not to mention that the first form makes localization easier between english and any of {French, Spanish, Italian, etc..}
Yes, I was going to make that point too.
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Hello experts, which advantages does one of these two methods
return (string.Format("Device #{0}", devNr));
return ("Device #" + devNr.ToString());have over the other one? They seem to produce identical results.
Ciao, luker