Deleting a number digit by digit on a calculator screen - iphone

Question

I want to delete a number digit by digit on the calculator screen but am only being able to delete the full number . Is there any method ?
-(IBAction)cancelInput:(float)result1{
NSString *myString = [[NSNumber numberWithFloat:result] stringValue];
int str=[myString length]-1;
NSString *newstring = [[NSNumber numberWithInt:str] stringValue];
calculatorScreen.text= [NSString stringWithFormat:newstring];
//NSLog(#"%d ",str);
}

Answer 1

Here you go,
NSString *myString = [[NSNumber numberWithFloat:result] stringValue];
myString = [myString substringToIndex:[myString length]-1];
calculatorScreen.text= myString;

Answer 2

int str=[myString length]-1 will only return the length of your string, say if your number is 9876, it will return 3(4-1) and your newstring will be 3.If you want to delete the last character you have to create substring of myString.
string = [string substringToIndex:[string length] - 1];

Answer 3

-(IBAction)backPressed:(UIButton *)sender
{
self.display.text=[self.display.text substringToIndex:[self.display.text length]-1];
if ( [self.display.text isEqualToString:#""] || [self.display.text isEqualToString:#"-"])
{
self.display.text =#"0";
}
}
This is the core function for the button. I took the liberty to add in the if feature so that it could handle some of the basic issues. As usual, replace display with your primary label. The If function help to counter check that your label does not become empty " " or have a negative sign "-" and will automatically replace it with "0", similar to clear in that aspect. in which you can run the clear method instead. But use
self.display.text =#"0";
for better clarification instead.

Answer 4

Use this code for it:
else if([character isEqualToString:(NSString*) Delete])
{
NSInteger index_of_char_to_remove=[_display length]-1;
if(index_of_char_to_remove>=0)
{
[_display deleteCharactersInRange:NSMakeRange(index_of_char_to_remove, 1)];
last_character_is_operator=NO;
}
}
When press 'C' it will checked this condition and delete the data one by one