Duplicate Case Value Error C

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like you, helping each other. Join them; it only takes a minute: Sign up switch statement duplicate error up vote -1 down vote favorite #include int main() { int a=5; switch(a) { case 1: ; case 2:; case 3+5:; case a:; } } Compiling this program, I get two errors: constant expression is required which is ok and expected. the second error says that duplicate case. Here case a: is duplicate with case 1:. Why second error is produced error? In a there is value of 5 and in case 1 it is 1. How 5 and 1 can conflict. c switch-statement share|improve this question edited Feb 26 '14 at 12:32 asked Feb 26 '14 at 12:16 user3335653 516 What do you want to achieve with: switch( a ) /* ... */ case a /* ... */ ? –Kiril Kirov Feb 26 '14 at 12:19 Not reproducable. –alk Feb 26 '14 at 12:23 1 with g++ I am getting second error error: expected ‘:’ before ‘;’ token , which compiler you are using ? –EmptyData Feb 26 '14 at 12:23 A case statments argument needs to be constant, so at least case a: is illegal. –alk Feb 26 '14 at 12:23 The second warning appears because your compiler is free to diagnose what it wants--especially for syntactically invalid input. –Jens Feb 26 '14 at 12:24 | show 1 more comment 5 Answers 5 active oldest votes up vote 2 down vote When a compiler encounters an error, it attempts to recover, and continue. This means that it tries to change the code to something it thinks was meant (or nothing at all) and just continue right after the erronous piece of code. Generally speaking, only the first compiler error is 100% correct, the following ones might just be "collateral damage" and have no real meaning at all. share|improve this answer answered Feb 26 '14 at 12:24 rubenvb 41.6k13103188 add a comment| up vote 2 d

here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Macro to avoid duplicate case value up vote 2 down vote favorite I am http://stackoverflow.com/questions/22041092/switch-statement-duplicate-error using a switch expression in C in order to evaluate the errno variable. According to the man page for send(): EAGAIN or EWOULDBLOCK The socket is marked nonblocking and the requested operation would block. POSIX.1-2001 allows either error to be returned for this case,and does not require these constants to have the same value, so a portable application should check for both possibilities. Since my application must be portable, I http://stackoverflow.com/questions/27509061/macro-to-avoid-duplicate-case-value have to do: switch (errno): case EWOULDBLOCK: case EAGAIN: //do whatever break; case EINTR: //... The problem is that for some platforms, EWOULDBLOCK and EAGAIN do have the same value, so when compiling I get: connection.cxx:190:5: error: duplicate case value case EWOULDBLOCK: ^ connection.cxx:189:5: error: previously used here case EAGAIN: ^ So I thought I could use a macro macro that depending on whether EWOULDBLOCK and EAGAIN have the same value or not for the platform adds that line to the code or omits it. Any idea on how to write that macro? c macros share|improve this question asked Dec 16 '14 at 16:14 user2891462 475518 add a comment| 2 Answers 2 active oldest votes up vote 8 down vote accepted Something like: #if EAGAIN != EWOULDBLOCK case EAGAIN: #endif case EWOULDBLOCK: edit: however if you're going to have many switch switch statements, a macro would be better than the conditional compilation. Something like: #if EAGAIN == EWOULDBLOCK #define MY_AGAIN EAGAIN #else #define MYAGAIN EAGAIN: case EWOULDBLOCK #endif Then to use it: case MY_AGAIN: You'll see that the colon is not part of the macro at the point where it is called: case ---->MACRO GOES HERE<-----: however in the second case, when expanded in the context of the or

but I'm getting an error. Here's the code. http://www.cplusplus.com/forum/beginner/101401/ 1
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#include int main() { bool loop; loop = 1; bool looptwo; looptwo = 1; double box; box = 0; char action; char actionA; char actionC; do{ std::cout << "\n You awake in a dark cave. All you can see duplicate case is a small fire in the distance.\n What would you like to do?\n"; std::cout << "\n[A] Walk to the fire.\n"; std::cout << "\n[B] Run to the fire.\n"; std::cout << "\n[C] Stay where you are. You are comfy, after all.\n"; std::cout << "\n[D] duplicate case value POOP YOURSELF. WHAT IS GOING ON?\n"; std::cout << "\n\n\n (Tip) for any choice, press 'o' to start from scratch!\n"; std::cin >> action; switch (action) { case 'a': loop = 0; std::cout << "\n You carefully approach the fire. Your vision remains dark and dull, but not for long. Slowly, you can see more clearly. By the fire you notice that there is a small box.\n"; if ( box == 2 ) {std::cout << "\n During your examination of the box, you start to hear a grumbling coming from the box. It starts shaking in your hands, to the point of your hands going numb.\n In your increasing panic, you...\n";} std::cout << "\n What would you like to do?\n"; std::cout << "\n[A] Examine the box.\n"