Home/ Questions/Recommendation for the error: jump to case label in switch statement in c++ error
Next
Answered
Poppy Roberts
  • 27
Asked: 2022-05-18T19:07:43+00:00 In:

Recommendation for the error: jump to case label in switch statement in c++ error

  • 27

. Advertisement .

..3..

. Advertisement .

..4..

I get the “Error: Jump to case label in switch statement in C++” error as the title says. How can I fix it so the error goes away? Here is my detail:

#include <iostream>
 int main() 
 {
  int choice;
  std::cin >> choice;
  switch(choice)
  {
  case 1:
  int i=0;
  break;
  case 2: // error here 
  }
 }

When I operated it, I received the error text:

Error: Jump to case label.

I appreciate any help from you.

switch-statement
Share

2 Answers

  1. Best Answer
    Expert

    The cause:

    This problem because declaration of variables in case will be shown in subsequent case unless HTML13 blocks are used. However, they won’t be initialized because the initialization code belongs to another case.

    Solution: 

    You can check whether foo equals 1 by the  following code. If it equals 1, all is fine but if it equals 2, then we’ll accidentally use i, it exists but contains garbage.

    switch(foo) {
case 1:
int i = 42; // i shows all the ways to the end of the switch which are existing 
dostuff(i);
break;
case 2:
dostuff(i*2); // i also is in scope here, but it is not initialized!
}

    You can solve this probblem by wrapping the case in an explicit block:

    switch(foo) {
 case 1:
 {
 int i = 42; // only within the { }, i can exist
 dostuff(i);
 break;
 }
 case 2:
 dostuff(123); // i can not used accidentally now
}

    Moreover, you also can describe a more fancy version of goto by using switch statements. Below is an analogous piece of code that has the same issue, but it uses a goto rather than a switch.

    int main() {
if(rand() % 2) // Toss a coin
goto end;

int i = 42;

end:
// We either can skip the declaration of i or not,
// but one of the two ways the variable i exists here, as
// variable scopes are resolved at compile time.
// Whether the *initialization* code is runned or not, eventhough,
// it depends on whether rand returned 0 or 1.
std::cout << i;
}
    • 17

  2. Problems are caused by the declaration of new variables within case statements. This problem can be solved by enclosing all case {} statements. 

    switch(choice)
{
 case 1: {
 // .......
 }break;
 case 2: {
 // .......
 }break;
 case 3: {
 // .......
 }break;
}
    • 8

Leave an answer

You must login to add an answer.

Need An Account,