how to use a while loop for switch case

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I have this code:
transactionType= input('1:withdraw 2:deposit 3:account balance 4:end use');
switch transactionType
case 1
.....
case 2
.....
case 3
.....
case 4
.....
otherwise
disp ('invalid')
I need to make it so that, if a number other than 1, 2, 3, or 4 is entered, it displays this message, but also lets me enter a number again.
So is there a way to do that using a while loop.

Accepted Answer

Walter Roberson
Walter Roberson on 9 Dec 2021
try_again = true;
while try_again
transactionType= input('1:withdraw 2:deposit 3:account balance 4:end use');
switch transactionType
case 1
if it works out
try_again = false;
end
So when you detect specifically that you are done then set the exit flag.
There is another way:
while true
transactionType= input('1:withdraw 2:deposit 3:account balance 4:end use');
switch transactionType
case 1
if everything works out
break;
end
do not break if you need to try again
Note that you would typically have an indefinite loop anyhow, to allow multiple transactions, continuing until the user ends (or a sanity check is reached)

More Answers (1)

Chunru
Chunru on 9 Dec 2021
repeat = true;
while repeat
transactionType= input('1:withdraw 2:deposit 3:account balance 4:end use');
repeat = false; % this ensures exit if input is valid
switch transactionType
case 1
.....
case 2
.....
case 3
.....
case 4
.....
otherwise
disp ('invalid')
repeat = true; % repeat if invalid
end
end

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