Refactoring: remove implicit conversion from QCString to const char *

This commit changes the following in relation to string use
- The implicit convert from 'QCString' to 'const char *' is removed
- Strings parameters use 'const QCString &' as much as possible in favor
  over 'const char *'
- 'if (s)' where s is a QCString has been replaced by 'if(!s.isEmpty())'
- data() now always returns a valid C-string and not a 0-pointer.
- when passing a string 's' to printf and related functions 'qPrint(s)' is
  used instead of 's.data()'
- for empty string arguments 'QCString()' is used instead of '0'
- The copy() operation has been removed
- Where possible 'qstrcmp(a,b)==0' has been replaces by 'a==b' and
  'qstrcmp(a,b)<0' has been replaced by 'a<b'
- Parameters of string type that were default initialized with '= 0' are
  no initialized with '= QCString()'

1 files changed, 2 insertions, 2 deletions

diff --git a/src/dia.h b/src/dia.h
index 2963ce0..bd0a378 100644
--- a/src/dia.h
+++ b/src/dia.h
@@ -22,8 +22,8 @@ class QCString;
 
 enum DiaOutputFormat { DIA_BITMAP , DIA_EPS };
 
-void writeDiaGraphFromFile(const char *inFile,const char *outDir,
-                           const char *outFile,DiaOutputFormat format);
+void writeDiaGraphFromFile(const QCString &inFile,const QCString &outDir,
+                           const QCString &outFile,DiaOutputFormat format);
 
 #endif