string-concatenation

问题 If I have two char arrays like so: char one[200]; char two[200]; And I then want to make a third which concatenates these how could I do it? I have tried: char three[400]; strcpy(three, one); strcat(three, two); But this doesn't seem to work. It does if one and two are setup like this: char *one = "data"; char *two = "more data"; Anyone got any idea how to fix this? Thanks 回答1: If 'one' and 'two' does not contain a '\0' terminated string, then you can use this: memcpy(tree, one, 200); memcpy(

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Should I use Java's String.format() if performance is important? I was wondering if is good to use String.format in Java apps instead of StringBuilder ... so, I just write a simple test, like this: public static void main(String[] args) { int i = 0; Long start = System.currentTimeMillis(); while (i < 10000) { String s = String.format("test %d", i); i++; } System.out.println(System.currentTimeMillis() - start); i

问题 I was reading this documentation page, http://developer.android.com/reference/android/util/Log.html. The section here caught my eye: Tip: Don't forget that when you make a call like Log.v(TAG, "index=" + i); that when you're building the string to pass into Log.d, the compiler uses a StringBuilder and at least three allocations occur: the StringBuilder itself, the buffer, and the String object. Realistically, there is also another buffer allocation and copy, and even more pressure on the gc.

问题 This question already has answers here : How to concatenate string variables in Bash (30 answers) Closed 3 years ago . How can I concat strings in shell? Is it just... var = 'my'; var .= 'string'; ? 回答1: How about this: var="${var}string" 回答2: It depends on the shell, but since question was tagged bash: var='my' var=$var'string' 回答3: No. For various reasons. # most sh-compatible shells var="my" var="$var string" # advanced shells var="my" var+=" string" 来源： https://stackoverflow.com/questions

问题 Sample Data: UniqueID Description ConsolidatedText Str1 Here is a sentence Here is a sentence Str2 And another sentence. And another sentence. And some words Str2 And some words Str3 123 123 Str4 abc abc ###" Str5 ### I have a number of records (~4000) each with a UniqueID value (text) and a text field (potentially quite lengthy) which is a user-entered description of the data. I need to consolidate the spreadsheet by concatenating all the descriptions into a single record where there are

问题 Sample Data: UniqueID Description ConsolidatedText Str1 Here is a sentence Here is a sentence Str2 And another sentence. And another sentence. And some words Str2 And some words Str3 123 123 Str4 abc abc ###" Str5 ### I have a number of records (~4000) each with a UniqueID value (text) and a text field (potentially quite lengthy) which is a user-entered description of the data. I need to consolidate the spreadsheet by concatenating all the descriptions into a single record where there are

问题 Is there any noticeable difference between the two lines? My coworker says that using += is "faster" but I don't see why they should be any different: string s1 = "hello"; string s2 = " world"; // Option 1 s1 += s2; // Option 2 s1.append(s2); To clarify, I am not asking about the usage differences between the two functions - I am aware that append() can be used for a wider variety of uses and that operator += is somewhat more specialized. What I care about is how this particular example gets

问题 This question already has answers here : How to concatenate string variables in Bash (30 answers) Closed 5 years ago . I am trying to download files from a database using wget and url. E.g. wget "http://www.rcsb.org/pdb/files/1BXS.pdb" So format of the url is as such: http://www.rcsb.org/pdb/files/($idnumber).pdb" But I have many files to download; so I wrote a bash script that reads id_numbers from a text file, forms url string and downloads by wget. !/bin/bash while read line do url="http:/

问题 Hi! Today I learned for xml path technique to concatenate strings in mssql. Since I've never worked with xml in mssql and google hasn't helped, I need to ask you. Let's imagine the default case. We need to concatenate some strings from a table: declare @xmlRepNames xml = ( select ', [' + report_name + ']' from ( select distinct report_order, report_name from #report ) x order by report_order for xml path(''), type) select stuff((select @xmlRepNames.value('.', 'nvarchar(max)')), 1, 1, '') So I

问题 (Related question that does not include sorting. It's easy to just use paste when you don't need to sort.) I have a less-than-ideally-structured table with character columns that are generic "item1","item2" etc. I would like to create a new character variable that is the alphabetized, comma-separated concatenation of these columns. So for example, in row 5, if item1 = "milk", item2 = "eggs", and item3 = "butter", the new variable in row 5 might be "butter, eggs, milk" I wrote a function f()