c-preprocessor

Here's a concrete example of what I want to do. Consider the string.Join function. Pre-.NET 4.0, there were only two overloads, both of which required a string[] parameter. As of .NET 4.0, there are new overloads taking more flexible parameter types, including IEnumerable<string> . I have a library which includes a Join function that does essentially what the .NET 4.0 string.Join function does. I was just wondering if I could make this function's implementation dependent on the .NET framework being targeted. If 4.0, it could simply call string.Join internally. If 3.5 or older, it could call

This question already has answers here : Closed 2 years ago . A riddle (in C) (4 answers) In the code shown below, nothing gets printed, which means the condition in the for loop fails. What could be the reason? I'm wondering because when I print TOTAL_ELEMENTS separately, it gives 5 , so naturally this must be 5-2=3 => -1<=3 , so it should print something. #define TOTAL_ELEMENTS (sizeof(array) / sizeof(array[0])) int array[] = { 23, 34, 12, 17, 204, 99, 16 }; int main() { int d; for (d = -1; d <= (TOTAL_ELEMENTS - 2); d++) { printf("%d\n", array[d + 1]); } return 0; } Can someone explain this

This question already has answers here : Closed 7 years ago . Possible Duplicate: # and ## in macros why the output of second printf is f(1,2) what is the order in which macro is evaluated? #include <stdio.h> #define f(a,b) a##b #define g(a) #a #define h(a) g(a) int main() { printf("%s\n",h(f(1,2))); printf("%s\n",g(f(1,2))); return 0; } output 12 f(1,2) From http://gcc.gnu.org/onlinedocs/cpp/Argument-Prescan.html#Argument-Prescan Macro arguments are completely macro-expanded before they are substituted into a macro body, unless they are stringified or pasted with other tokens. After

I occasionally write code something like this: // file1.cpp #define DO_THIS 1 #if DO_THIS // stuff #endif During the code development I may switch the definition of DO_THIS between 0 and 1. Recently I had to rearrange my source code and copy some code from one file to another. But I found that I had made a mistake and the two parts had become separated like so: // file1.cpp #define DO_THIS 1 and // file2.cpp #if DO_THIS // stuff #endif Obviously I fixed the error, but then thought to myself, why didn't the compiler warn me? I have the warning level set to 4. Why isn't #if X suspicious when X

Why doesn't the commented out line in the following program compile? #include <iostream> #include <vector> using namespace std; #define F1(a) 1 int F2(vector<int>) { return 2; } int main() { vector<int> v; v = vector<int>{1,2,3}; cout << F1( v ) << endl; //The following line doesn't compile. The error is: //error: macro "F" passed 3 arguments, but takes just 1 //cout << F1( vector<int>{1,2,3} ) << endl; // <- error! cout << F1( vector<int>({1,2,3}) ) << endl; cout << F1( (vector<int>{1,2,3}) ) << endl; cout << F2( v ) << endl; //The following line compiles fine cout << F2( vector<int>{1,2,3} )

I discovered that Microsoft Visual Studio compiler and gcc preprocess the following small snippet differently: # define M3(x, y, z) x + y + z # define M2(x, y) M3(x, y) # define P(x, y) {x, y} # define M(x, y) M2(x, P(x, y)) M(a, b) 'gcc -E' gives the following: a + {a + b} , while 'cl /E' issues a warning about missing macro argument and produces the following output: a + {a, b} + It seems that commas that came from nested macro expansions are not considered to be argument separators. Unfortunately, I found no description of the algorithm implemented in cl preprocessor, and so I'm not sure

I have encountered a small problem with my T4 code generation. I have broken my T4 templates up into separate files and placed them in various directories, I have done this so parts of my code generation may be re-used in multiple projects, e.g. model generation, repository generation and service generation all include a core EntityGeneration.tt file. Unfortunately, when TextTemplating resolves my nested includes, it builds up a long #line pre-processor directive in its generated .cs file, combining all of the relative paths to the lowest level included file. Unfortunately, as this path is