How to split a string literal across multiple lines in C Objective-C

Question

I have a pretty long sqlite query   const char  sql query    SELECT statuses word id FROM lang1 words  statuses WHERE statuses word id   lang1 words word id ORDER BY lang1 words word ASC     How can I break it in a number of lines to make it easier to read  If I do the following   const char  sql query    SELECT word id                         FROM table1  table2                         WHERE table2 word id   table1 word id                         ORDER BY table1 word ASC     I am getting an error   Is there a way to write queries in multiple lines

User · Answer

GCC adds C   multiline raw string literals as a C extension  C  11 has raw string literals as mentioned at  https   stackoverflow com a 44337236 895245  However  GCC also adds them as a C extension  you just have to use -std gnu99 instead of -std c99  E g    main c   include  lt assert h gt   include  lt string h gt   int main void        assert strcmp R   a b       na nb n      0       Compile and run   gcc -o main -pedantic -std gnu99 -Wall -Wextra main c   main   This can be used for example to insert multiline inline assembly into C code  How to write multiline inline assembly code in GCC C     Now you just have to lay back  and wait for it to be standardized on C20XY   C   was asked at  C   multiline string literal  Tested on Ubuntu 16 04  GCC 6 4 0  binutils 2 26 1

User · Answer

One more solution for the pile  change your  m file to  mm so that it becomes Objective-C   and use C   raw literals  like this   const char  sql query   R  SELECT word id                            FROM table1  table2                            WHERE table2 word id   table1 word id                            ORDER BY table1 word ASC      Raw literals ignore everything until the termination sequence  which in the default case is parenthesis-quote   If the parenthesis-quote sequence has to appear in the string somewhere  you can easily specify a custom delimiter too  like this   const char  sql query   R T3RM N8                                    SELECT word id                                   FROM table1  table2                                   WHERE table2 word id   table1 word id                                   ORDER BY table1 word ASC                           T3RM N8

User · Answer

Extending the Quote idea for Objective-C    define NSStringMultiline        NSString alloc  initWithCString    VA ARGS   encoding NSUTF8StringEncoding   NSString  sql   NSStringMultiline      SELECT name  age     FROM users     WHERE loggedin   true

User · Answer

There are two ways to split strings over multiple lines   Using    All lines in C can be split into multiple lines using     Plain C   char  my string    Line 1                      Line 2     Objective-C   NSString  my string     Line1                           Line2     Better approach  There s a better approach that works just for strings   Plain C   char  my string    Line 1                      Line 2     Objective-C   NSString  my string     Line1                           Line2         the second   is optional   The second approach is better  because there isn t a lot of whitespace included  For a SQL query however  both are possible   NOTE  With a  define  you have to add an extra     to concatenate the two strings   Plain C    define kMyString  Line 1                      Line 2

User · Answer

There s a trick you can do with the pre-processor  It has the potential down sides that it will collapse white-space  and could be confusing for people reading the code  But  it has the up side that you don t need to escape quote characters inside it    define QUOTE         VA ARGS   const char  sql query   QUOTE      SELECT word id     FROM table1  table2     WHERE table2 word id   table1 word id     ORDER BY table1 word ASC      the preprocessor turns this into   const char  sql query    SELECT word id FROM table1  table2 WHERE table2 word id   table1 word id ORDER BY table1 word ASC     I ve used this trick when I was writing some unit tests that had large literal strings containing JSON   It meant that I didn t have to escape every quote character

User · Answer

An alternative is to use any tool for removing line breaks  Write your string using any text editor  once you finished  paste your text here and copy it again in xcode

User · Answer

You could also go into XCode -  Preferences  select the Indentation tab  and turn on Line Wrapping   That way  you won t have to type anything extra  and it will work for the stuff you already wrote   -   One annoying thing though is     if  you re long on indentation      amp  amp  short on windows                then your code will                 end up squished                      against th                          e side                              li                               k                               e                                t                               h                               i                               s

User · Answer

You can also do   NSString   query     SELECT   FROM foo                        WHERE                          bar   42                          AND baz   datetime                          ORDER BY fizbit ASC

User · Answer

I am having this problem all the time  so I made a tiny tool to convert text to an escaped multi-line Objective-C string   http   multilineobjc herokuapp com   Hope this saves you some time

[c] How to split a string literal across multiple lines in C / Objective-C?

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