C / C++

See also C and C++.

C

References

• The C Library Reference Guide
• C Preprocessor reference
• manpage manpages-dev
• manpage manpages-posix-dev

sudo apt-get install manpages-dev manpages-posix-dev

Tips

Variadic Macros

See reference here.

#define eprintf(...) fprintf (stderr, __VA_ARGS__)
/* eprintf ("%s:%d: ", input_file, lineno)
          ==>  fprintf (stderr, "%s:%d: ", input_file, lineno) */
#define eprintf(args...) fprintf (stderr, args)
#define eprintf(format, ...) fprintf (stderr, format, __VA_ARGS__)

An handy macro hack that counts the number of parameters passed before expansion (See [1] and [2]):

 /* The PP_NARG macro returns the number of arguments that have been
  * passed to it. This compensates for lack of __VA_NARGS__.
  * Macros written by Laurent Deniau See http://en.wikipedia.org/wiki/Variadic_macro.
  */ 

#define PP_NARG(...) \ 
         PP_NARG_(__VA_ARGS__,PP_RSEQ_N()) 
#define PP_NARG_(...) \ 
         PP_ARG_N(__VA_ARGS__) 
#define PP_ARG_N( \ 
          _1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \ 
         _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \ 
         _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \ 
         _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \ 
         _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \ 
         _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \ 
         _61,_62,_63,N,...) N 
#define PP_RSEQ_N() \ 
         63,62,61,60,                   \ 
         59,58,57,56,55,54,53,52,51,50, \ 
         49,48,47,46,45,44,43,42,41,40, \ 
         39,38,37,36,35,34,33,32,31,30, \ 
         29,28,27,26,25,24,23,22,21,20, \ 
         19,18,17,16,15,14,13,12,11,10, \ 
         9,8,7,6,5,4,3,2,1,0 

/* Some test cases */ 
PP_NARG(A) -> 1 
PP_NARG(A,B) -> 2 
PP_NARG(A,B,C) -> 3 
PP_NARG(A,B,C,D) -> 4 
PP_NARG(A,B,C,D,E) -> 5 
PP_NARG(1,2,3,4,5,6,7,8,9,0, 
         1,2,3,4,5,6,7,8,9,0, 
         1,2,3,4,5,6,7,8,9,0, 
         1,2,3,4,5,6,7,8,9,0, 
         1,2,3,4,5,6,7,8,9,0, 
         1,2,3,4,5,6,7,8,9,0, 
         1,2,3) -> 63

Temporary variable names for Macro

/* UNIQ(x) creates a unique variable name that depends on the current source line as returned by __LINE__. We need
   Several intermediate macros because identifier are not expanded in macro if they are used along with # or ## in
   macro definition.

   Example:   #define SCAN_MY(var,n)   {int UNIQ(x); for(UNIQ(x)=0; UNIQ(x)<n; ++UNIQ(x)) printf(var[UNIQ(x)]);}
*/
#define UNIQ__(x,y) x ## y
#define UNIQ_(x,y)  UNIQ__(x,y)
#define UNIQ(x)     UNIQ_(x,__LINE__)

C++

References

See also C reference above.

• www.cplusplus.com — C++ Reference
• Including C Language Library
• and ... IOStream Library
• SGI — Standard Template Library Programmer's Guide
• Evolving a language in and for the real world: C++ 1991-2006, Bjarne Stroustrup (pdf)
• manpage stl-manual (from SGI)

sudo apt-get install stl-manual
ln -s /usr/share/doc/stl-manual/html /var/www/sgi        # Now the manual is available at http://localhost/sgi

References - local copy

# Make a local copy of www.cplusplus.com - use option -P http://proxy:port if needed
httrack http://www.cplusplus.com/ -W -O /var/www -%v "-www.cplusplus.com/forum/*" "-www.cplusplus.com/src/*" "-www.cplusplus.com/member/*"

Benchmark

Between compilers

• g++
• EKOPath4, a recently open-sourced compiler with much better performance than gcc/g++.
• Intel compiler
• pathCC, PathScale compiler

Between languages

• C++ reported to be the fastest language, even faster than C and java. See The Computer Language Benchmarks Game
• C++ the Clear Winner In Google's Language Performance Tests

Nested Classes

See Nested classes on ibm.com.

Tips

Problem	Solution
Overloading operators i++ or ++i See [3] for more details.	class Number { public: // prefix ++ - Must return (*this) Number& operator++ (); // postfix ++ - Must never return (*this) by reference Number operator++ (int); // ... OR .... void operator++ (int); };
Reset ostringstream	ostringstream oss; oss << "Hello," << 123 << endl; string s = oss.str(); oss.str(""); // oss empty now - we can reuse it oss << "World!" << 456 << endl;

Security Tips

Problem	Solution
Use mlock() to prevent a section of memory from swapping to disk (source: "Building Secure Software," John Viega & Gary McGraw)

Tools

GNU cflow

GNU cflow analyzes a collection of C source files and prints a graph, charting control flow within the program.

GNU cflow is able to produce both direct and inverted flowgraphs for C sources. Optionally a cross-reference listing can be generated. Two output formats are implemented: POSIX and GNU (extended).

<iostream.h> or <iostream>

• <iostream> is the standard compliant library. <iostream.h> is deprecated since many many years.
• <iostream> contains a set of templatized I/O classes which support both narrow and wide characters (by contrast, <iostream.h> classes are confined to char exclusively).
• Third, the C++ standard specification of iostream's interface was changed in many subtle aspects. Consequently, the interfaces and implementation of <iostream> differ from <iostream.h>.
• Finally, <iostream> components are declared in namespace std whereas <iostream.h> components are declared in the global scope.

Note that both libraries cannot be mixed in one program.