From: richard.nospam@gmail.invalid   
      
   On 22/10/2025 10:32, Janis Papanagnou wrote:   
   > On 22.10.2025 10:56, pozz wrote:   
   >>   
   >>> Switch statements without a default case can lead to unexpected   
   >>> behavior and incomplete handling of all possible cases. When a switch   
   >>> statement lacks a default case, if a value is encountered that does   
   >>> not match any of the specified cases, the program will continue   
   >>> execution without any defined behavior or handling.   
   >>   
   >> Maybe I misunderstood that sentence caused by my bad English. I knew   
   >> that in case the switch value is not present in any case inside the   
   >> switch, the program continues without doing anything (in the switch) and   
   >> without any problem.   
   >>   
   >> int x = 3;   
   >> switch(x) {   
   >>    case 1: printf("Hello");break;   
   >>    case 2: printf("World");break;   
   >> }   
   >>   
   >> Will the program execution continue without any defined behaviour?   
   >   
   > Your program fragment is well defined.   
   >   
   > What the poster certainly tried to express was that in case you   
   > haven't implemented a complete list of all possible cases and   
   > also not provided a 'default' to catch all non-specified cases,   
   > then you might get in troubles with your program, probably by   
   > possible oversights, future extensions, new data, and whatnot.   
   >   
   > Personally I have the habit to always define a default branch,   
   > and even if that default is impossible to reach you'll find an   
   > error message (like "internal error with unexpected value...")   
   > generated at that place.   
   >   
   Use an enum, and the compiler will warn you ...   
      
   $ cat x.c   
   #include    
      
   enum x {A, B, C};   
      
   int main(void)   
   {   
        enum x x = C;   
      
        switch (x)   
        {   
            case A:   
                printf("A\n");   
                break;   
      
            case B:   
                printf("B\n");   
                break;   
        }   
      
        return 0;   
   }   
      
   $ gcc -Wall x.c   
   x.c: In function ‘main’:   
   x.c:9:9: warning: enumeration value ‘C’ not handled in switch [-Wswitch]   
        9 |         switch (x)   
          |         ^~~~~~   
      
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