When practicing the switch statement in Ubuntu, if break is not added in the case statement, the warning message will pop up, causing the program to fail to compile,

root@root:~/code$ g++ -Wall -W test_switch.c -o test_switch 
test_switch.c: In function ‘int main()’:
test_switch.c:13:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
   13 |    printf("1\n");
      |    ~~~~~~^~~~~~~~~~~~~
test_switch.c:15:3: note: here
   15 |   case 3:
      |   ^~~~
test_switch.c:16:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
   16 |    printf("3\n");
      |    ~~~~~~^~~~~~~~~~~~~
test_switch.c:18:3: note: here
   18 |   case 5:
      |   ^~~~

At this time, adding – W when compiling the code can shield the alarm, and the code can be compiled normally

root@root:~/code$ g++ -Wall -W test_switch.c -o test_switch -w