If() statement text boxes

gogoraj · 10-11-2011, 04:41 AM

If I wanted a program to use a certain method only if certain text boxes are filled, how would I do that?

I.e. if text box x and y and z have (any) values then do this
else if text box a and b and c have (any) values then do this.

Meredi86 · 10-11-2011, 06:45 AM

Create text boxes.
Hook up IBOutlets for the text boxes (ties the text box to a "name")
write out method for the text boxes
create if statements:

Code:

if (textField == self.textFieldName) {
if (self.textFieldName == nil) {
execute statement
}
}

**baja_yu** · 10-11-2011, 08:18 AM

Besides checking for nil you should also check if it equals @"" (empty string), maybe even trim the textfield's string before checking.

gogoraj · 10-11-2011, 11:02 AM

Quote:

Originally Posted by Meredi86

Create text boxes.
Hook up IBOutlets for the text boxes (ties the text box to a "name")
write out method for the text boxes
create if statements:

Code:

if (textField == self.textFieldName) {
if (self.textFieldName == nil) {
execute statement
}
}

So if I wanted say 2 text boxes to have values how would I put that in one?
e.g. if (textField == self.textFieldName)
AND (textField2 == self.textFieldName2) {
etc.

Meredi86 · 10-11-2011, 11:22 AM

Google is great at searching for the operators that take the place of AND/OR.

AND = &&
OR = ||

so

Code:

if (self.TextFieldA == nil) && (self.textFieldB == nil) {
statements
}

would mean that textFieldA must = nil AND textFieldB must = nil for the statement to execute

gogoraj · 10-11-2011, 11:26 AM

Quote:

Originally Posted by Meredi86

Google is great at searching for the operators that take the place of AND/OR.

AND = &&
OR = ||

so

Code:

if (self.TextFieldA == nil) && (self.textFieldB == nil) {
statements
}

would mean that textFieldA must = nil AND textFieldB must = nil for the statement to execute

Yes it would. In fact there are three things that have to != nil.
Basically I want it to detect out of 5 text boxes, which ones actually have values entered and to choose an IBAction accordingly.
Where would I position my If statements in my code?

**dljeffery** · 10-11-2011, 09:16 PM

Quote:

Originally Posted by gogoraj

Yes it would. In fact there are three things that have to != nil.
Basically I want it to detect out of 5 text boxes, which ones actually have values entered and to choose an IBAction accordingly.
Where would I position my If statements in my code?

Please show your code that doesn't work.

gogoraj · 10-12-2011, 01:08 AM

Quote:

Originally Posted by dljeffery

Please show your code that doesn't work.

if (txtUvalue != nil && txtvValue != nil && txtTvalue!= nil )
{- (IBAction) calculateSvalue1: (id) sender
{
float uValue = [txtUvalue.text floatValue];
float vValue = [txtVvalue.text floatValue];
float tValue = [txtTvalue.text floatValue];
float sValue = 0.5 * (uValue + vValue) * tValue;

lblSvalue.text = [NSString stringWithFormat:@"%0.002f", sValue] ;
}
}

I keep getting an error 'expected (' before the if.

Meredi86 · 10-12-2011, 03:05 AM

Code:

if (txtUvalue != nil && txtvValue != nil && txtTvalue!= nil )
{- (IBAction) calculateSvalue1: (id) sender
{ 
float uValue = [txtUvalue.text floatValue];
float vValue = [txtVvalue.text floatValue];
float tValue = [txtTvalue.text floatValue];
float sValue = 0.5 * (uValue + vValue) * tValue; 

lblSvalue.text = [NSString stringWithFormat:@"%0.002f", sValue] ;
}
}

Use these tags to surround your code - makes it easier to read

[ code ] [/ code ] (but without the white space).

Basically you need to treat each evaluation as a separate one:

Code:

if ((txtUvalue != nil) && (txtvValue != nil) && (txtTvalue!= nil))
{- (IBAction) calculateSvalue1: (id) sender
{ 
float uValue = [txtUvalue.text floatValue];
float vValue = [txtVvalue.text floatValue];
float tValue = [txtTvalue.text floatValue];
float sValue = 0.5 * (uValue + vValue) * tValue; 

lblSvalue.text = [NSString stringWithFormat:@"%0.002f", sValue] ;
}
}

This is one of my OR setups:

Code:

if (([elementName isEqualToString:@"status"]) || ([elementName isEqualToString:@"message"]) || ([elementName isEqualToString:@"sessionKey"]))

The [ brackets are for the syntax within the evaluation - and your code shouldn't require these. but it shows you generally how they are made up

Duncan C · 10-12-2011, 08:27 AM

Quote:

Originally Posted by gogoraj

if (txtUvalue != nil && txtvValue != nil && txtTvalue!= nil )
{- (IBAction) calculateSvalue1: (id) sender
{
float uValue = [txtUvalue.text floatValue];
float vValue = [floatValue];
float tValue = [txtTvalue.text floatValue];
float sValue = 0.5 * (uValue + vValue) * tValue;

lblSvalue.text = [NSString stringWithFormat:@"%0.002f", sValue] ;
}
}

I keep getting an error 'expected (' before the if.

Ok, several things.

You say you keep getting 'expected (' before the if. If you're getting an error before the if statement, you need to post the code that appears before the if statement.

Next: I think you are getting some bad advice about how to check if a field is blank. I'm fairly certain that you will never get nil back from the text property of a text field. You will get an empty string instead.

So, ytxtVvalue.textour if statement should read:

Code:

if ([txtUvalue.text length] != 0 && 
  [txtvValue.text length] != 0 &&
  [txtTvalue.text length] != 0)

Second, your code inside the "{" and "}" brackets is the declaration of an IBAction method. That is not valid syntax. You need to put regular statements inside the brackets, not a method declaration.

When do you check to see if these fields are blank and update your result field? On a button push?

If it is on a button push, your code might look like this:

Code:

- (IBAction) buttonAction: (id) sender;
{
  if ([txtUvalue.text length] != 0 && 
    [txtvValue.text length] != 0 &&
    [txtTvalue.text length] != 0)
  {
    float uValue = [txtUvalue.text floatValue];
    float vValue = [txtvValue.text floatValue];
    float tValue = [txtTvalue.text floatValue];
    float sValue = 0.5 * (uValue + vValue) * tValue;  
    
    lblSvalue.text = [NSString stringWithFormat:@"%0.002f", sValue] ;
  }
}

Meredi86 · 10-12-2011, 08:47 AM

Quote:

Next: I think you are getting some bad advice about how to check if a field is blank. I'm fairly certain that you will never get nil back from the text property of a text field. You will get an empty string instead.

Kind of two reasons i had gone down that line:

1, Any advice from any forum should get checked over first unless there are a good few of the top posters agreeing on the issue, so here was a way of building in a mistake that could get found and explained by someone else - just as Duncan has and to stop the idea of getting everything done for you

.

2, i have had text fields before that when nothing has been entered they have saved a nil value. this was one of the things that caused me a big headache in getting my web service to tie in properly, every time i sent something there would be nil's there from the lack of user input, which in turn later returned the data and displayed "nil" in a bunch of fields - not to snazzy to look at!!

So in my app i now check the text fields like this:

Code:

if(textField != nil)
            {
            self.savedName = textField.text;
            }

in order to prevent saving "nil" as the "string" that was entered. Maybe its not the most elegant of solutions, but it is one that has been working 100% for me. Looking at Duncan's post though i would preferably switch to his method (app is in review so a bit late now) as it looks slightly more robust than my solution.

gogoraj · 10-12-2011, 01:49 PM

Quote:

Originally Posted by Duncan C

Ok, several things.

You say you keep getting 'expected (' before the if. If you're getting an error before the if statement, you need to post the code that appears before the if statement.

Next: I think you are getting some bad advice about how to check if a field is blank. I'm fairly certain that you will never get nil back from the text property of a text field. You will get an empty string instead.

So, ytxtVvalue.textour if statement should read:

Code:

if ([txtUvalue.text length] != 0 && 
  [txtvValue.text length] != 0 &&
  [txtTvalue.text length] != 0)

Second, your code inside the "{" and "}" brackets is the declaration of an IBAction method. That is not valid syntax. You need to put regular statements inside the brackets, not a method declaration.

When do you check to see if these fields are blank and update your result field? On a button push?

If it is on a button push, your code might look like this:

Code:

- (IBAction) buttonAction: (id) sender;
{
  if ([txtUvalue.text length] != 0 && 
    [txtvValue.text length] != 0 &&
    [txtTvalue.text length] != 0)
  {
    float uValue = [txtUvalue.text floatValue];
    float vValue = [txtvValue.text floatValue];
    float tValue = [txtTvalue.text floatValue];
    float sValue = 0.5 * (uValue + vValue) * tValue;  
    
    lblSvalue.text = [NSString stringWithFormat:@"%0.002f", sValue] ;
  }
}

Thanks, this has solved it. Most of my values are working perfectly now!
The only problem now is trying to solve a quadratic in the IBAction...
But that will come later. Thanks!