string-literals

问题 I got a problem with C programming string concatenation. Why strcat(dest, "\something") will not have the backslash copied to dest ? You may wish to follow the example. #include <stdio.h> #include <stdlib.h> #include <string.h> int main() { char *dest = ""; char *test = "how \something"; dest = (char *)malloc((strlen(test) + 1) * sizeof(char)); strcat(dest, test); // Expect to see "how \something", but showed "how something" printf("%s\n", dest); free(dest); return 0; } 回答1: backslash not

问题 I am starting writing a lexical analyzer for my programming language. String literals in this language start with a " and end when an unescaped " is encountered. Everything inside (including newlines) is preserved, except escape sequences (the usual \n s, \t s, \" s etc plus a way of escaping a character by using its ASCII code, e.g. \097 or \97 ). This is the code I have written so far: %{ #include <iostream> #define YY_DECL extern "C" int yylex() std::string buffstr; %} %x SSTATE %% \" {

问题 After executing String S1 = "hello"; JVM will create a String object in SCP and that object will hold an array of char in value field like s1.value = {'h', 'e', 'l', 'l', 'o'} And when we say String s2 = new String("hello"); And according to the source code of String class after constructor execution s2.value will also become "hello".value which will be similar to s1.value . public String(String original) { this.value = original.value; this.hash = original.hash; } So every time we create

问题 One of my Join key-selectors looks like this: x => x.A + "-" + x.B NHibernate makes "-" an extra parameter. This parameter gets the SQL type nvarchar and so the whole statement gets converted on the SQL Server from varchar to nvarchar . The problem with this is, that SQL Server has a huge problem if the queried column is of type varchar instead of nvarchar . This is because the column is of another type than the parameter and so the index can't be used . I cannot change the type of the column

问题 I need to parse byte string which spans more than one line in the source code. Like this self.file.write(b'#compdef %s\n\n' '_arguments -s -A "-*" \\\n' % (self.cmdName,)) this line throws the following exception builtins.SyntaxError: cannot mix bytes and nonbytes literals which can be fixed in the following way self.file.write(b'#compdef %s\n\n\'\'_arguments -s -A "-*" \\\n' % (self.cmdName,)) Notice the backslashes after \n . but this fix does the follow the project rules of less than 79

问题 I'm referring to the syntax for writing strings in code, including multiline strings and verbatim strings. (Context: I'm working on a tool that scans code, and it's important to determine when tokens are inside a string.) Thanks! 回答1: Here's a quick breakdown between languages Managed C++: Supports string literals much in the way that vanilla C,C++ or C# does. That is strings are designated by " and allow for character escape sequences in the middle via a \. C#: Supports normal string

问题 I have a wide char literal: const wchar_t* charSet = L" !\"#$%&'()*+,-./0123456789:;<=>?\n" L"@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_\n" L"`abcdefghijklmnopqrstuvwxyz{|}~\n"; When I pass it into text processor '\'(backslash) isn't there.Now if I put instead \\ it I am getting compile time error: "missing closing quote" So how do I put backslash into such a char string? 回答1: As for your original code L" !\"#$%&'()*+,-./0123456789:;<=>?\n" you simply missed escaping the quote character " again.

问题 So I want to do the traditional thing to do with the stringizing operator in a macro: #define FOO(x) foo(#x, (x)) However I need to use a string literal prefix: http://en.cppreference.com/w/cpp/language/string_literal Which is a problem because if I need a UTF-32 string literal I try to do this: #define FOO(x) foo(U#x, (x)) But gcc 4.9.2 complains: error: 'U' was not declared in this scope Is there a way to make the compiler treat the U as a prefix to the stringized macro variable? 回答1: Yes,

问题 REPL: scala> val a = "hello\nworld" a: String = hello world scala> val b = """hello | world""" b: String = hello world scala> a == b res0: Boolean = true Worksheet: val a = "hello\nworld" //> a : String = hello //| world val b = """hello world""" //> b : String = hello //| world a == b //> res0: Boolean = true Normal Scala code: val a = "hello\nworld" val b = """hello world""" println(a) println(b) println(a == b) Output: hello world hello world false Why does the comparison yield true in the

问题 I have a function, that is templated to match every std::basic_string instantiation: template <typename _valueType> void addFoo(std::basic_string<_valueType>& string_) { string_ += "foo"; } I want "foo" to be _valueType -dependent literal. I would like not to use specialization, because in the actual project I have whole class templated and it would be a lot of work. I am currently using if constexpr in function body, but problems start, when I have function taking default parameter like this