How to stop while loop in C / C++? What happens if no break statement in switch...case?
When using switch...case statement in C / C++. We often wonder, "Should we use break statement in switch...case?" or "What happens if no break statement in switch...case?".
So, what would switch...case look like without a break statement. Does it work as well as we want it to? Let's start learning with us.
What happens if no break statement in switch...case?
break statement enables program execution to exit the switch construct. Without it, execution continues evaluating the following case statements.Make sure you learn and understand the switch...case statement. Let's review the syntax of the switch...case statement.
switch (expression) {
case constant1:
// code to be executed if
// expression is equal to constant1;
break;
case constant2:
// code to be executed if
// expression is equal to constant2;
break;
.
.
.
default:
// code to be executed if
// expression doesn't match any constant
}Suppose, in the switch...case statement, there are two cases, case1 and case2. Then we have 4 possibilities as follows:
Case1has a break statement andcase2doesn't.Case2has a break statement andcase1doesn't.- Both
case1andcase2have a break statement. - Neither
case1norcase2have a break statement.
Now we will take a closer look at each possibility.
Case1 has a break statement and case2 doesn't:
- If condition
case1is true. Then the code block insidecase1is executed and exitsswitch...case. - If condition
case1is false and conditioncase2is true. Then the block of code insidecase2is executed andcase1is not.
switch(expression){
case1 constant:
//block code 1
break;
case2 constant:
//block code 2
}Example:
#include <iostream>
using namespace std;
int main() {
int a;
cout<<"Enter a number: ";
cin>>a;
switch(a){
case 1:
cout<<"hello, i'm case 1\n";
a++;
break;
case 2:
cout<<"hello, i'm case 2\n";
}
cout<<"\n-------------------------------\n";
cout<<"This program is posted at learnnc.com";
return 0;
}Output:
Case2 has a break statement and case1 doesn't:
- If the condition of
case1is true. Then, the code block insidecase1is executed and continues to consider the condition ofcase2. - If condition
case1is false and conditioncase2is true. Then the block of code insidecase2is executed andcase1is not.
switch(expression){
case1 constant:
//block code 1
case2 constant:
//block code 2
break;
}Example:
#include <iostream>
using namespace std;
int main() {
int a;
cout<<"Enter a number: ";
cin>>a;
switch(a){
case 1:
cout<<"hello, i'm case 1\n";
a++;
case 2:
cout<<"hello, i'm case 2\n";
break;
}
cout<<"\n-------------------------------\n";
cout<<"This program is posted at learnnc.com";
return 0;
}Output:
Both case1 and case2 have a break statement:
- If condition
case1is true. Then the code block insidecase1is executed and exitsswitch...case. - If condition
case1is false and conditioncase2is true. Then the block of code insidecase2is executed andcase1is not.
switch(expression){
case1 constant:
//block code 1
break;
case2 constant:
//block code 2
break;
}Example:
#include <iostream>
using namespace std;
int main() {
int a;
cout<<"Enter a number: ";
cin>>a;
switch(a){
case 1:
cout<<"hello, i'm case 1\n";
a++;
break;
case 2:
cout<<"hello, i'm case 2\n";
break;
}
cout<<"\n-------------------------------\n";
cout<<"This program is posted at learnnc.com";
return 0;
}Output:
.PNG)
Neither case1 nor case2 have a break statement:
- If the condition of
case1is true. Then, the code block insidecase1is executed and continues to consider the condition ofcase2. - If condition
case1is false and conditioncase2is true. Then the block of code insidecase2is executed andcase1is not.
switch(expression){
case1 constant:
//block code 1
case2 constant:
//block code 2
}Example:
#include <iostream>
using namespace std;
int main() {
int a;
cout<<"Enter a number: ";
cin>>a;
switch(a){
case 1:
cout<<"hello, i'm case 1\n";
a++;
case 2:
cout<<"hello, i'm case 2\n";
}
cout<<"\n-------------------------------\n";
cout<<"This program is posted at learnnc.com";
return 0;
}Output:
Should we use break statement in switch...case?
switch...case, we should use break statement. This helps us avoid unexpected errors.-
If you don't include
breakstatement in any of case then all the case below will be executed and until it seesbreakstatement . -
And if you don't include
breakstatement in default then it will cause no effect as there are not any case below this 'Default' case. -
And not using
breakstatement generally considered as a bad practice but some time it may also come handy because of its fall-through nature.
We have an example that checks even or odd numbers. Please see the results when using the break statement and not using it.
Example: Checks Even or Odd numbers.
Using break statement:
#include <iostream>
using namespace std;
int main() {
int number, result;
cout<<"Enter a number: ";
cin>>number;
result = number % 2;
switch(result){
case 0:
cout<<"This is a even number.";
break;
case 1:
cout<<"This is a odd number.";
break;
}
cout<<"\n-------------------------------\n";
cout<<"This program is posted at learnnc.com";
return 0;
}Output:
Do not use the break statement:
#include <iostream>
using namespace std;
int main() {
int number, result;
cout<<"Enter a number: ";
cin>>number;
result = number % 2;
switch(result){
case 0:
cout<<"This is a even number.";
case 1:
cout<<"This is a odd number.";
}
cout<<"\n-------------------------------\n";
cout<<"This program is posted at learnnc.com";
return 0;
}Output:
