Why is exist(variable,'var') not seeing a variable?

I have a function to which a variable is passed. The variable exists:

'signedOrNot = signed'

When I call 'exist signedOrNot var' it is found:

ans = 1

But when I use exist(signedOrNot,'var'), as I would in an if statement, it is not:

ans = 0

Any thoughts?

Answer 1

[Fangjun Jiang]

exist('signedOrNot','var')

[Bogdan Dzyubak]

Right, of course... Thanks for reminding.

Answer 2

[Steven Lord]

This line of code tests whether the variable with the name signedOrNot exists in the workspace.

exist('signedOrNot', 'var')

This line of code tests whether the variable whose name is stored in the variable signedOrNot exists in the workspace.

exist(signedOrNot, 'var')

Compare:

% if a variable by this name exists, choose a different name
signedOrNot = 'thisVariableShouldNotExist';

passingName = exist('signedOrNot', 'var') % true, signedOrNot exists
passingContentsOfVariable = exist(signedOrNot, 'var') % false, thisVariableShouldNotExist doesn't

with:

x = 42;
signedOrNot = 'x';

passingName = exist('signedOrNot', 'var') % true, signedOrNot exists
passingContentsOfVariable = exist(signedOrNot, 'var') % true, x exists