Objective-c problem totalling an array by looping through it

I have this code wich accepts an array of income objects from Core Data.

- (void)totalIncome:(NSMutableArray *)IncomesArray {
    int i;
    int total;
    for (i = 0; i < [IncomesArray count]; ++i)
    {
        Income *income = [IncomesArray objectAtIndex:i];

   开发者_JS百科     total += (int)[income value];
        NSLog(@"%@", total);
    }
    self.totalIncomes = [[NSNumber alloc] initWithInt:(int)total];
    NSLog(@"%.2f", self.totalIncomes);
}

But the line NSLog(@"%@", total); causes an EXEC BAD ACCESS error. Is there something obvious I have done wrong. Also if I remove the log nothing is added to totalIncomes which is declared in my header file as a NSNumber. Thanks.

---

How about this:

- (void)totalIncome:(NSMutableArray *)IncomesArray {
    NSNumber *total = [IncomesArray valueForKeyPath:@"@sum.value"];
    NSLog(@"total: %@", total);
}

---

total is an int. use NSLog(@"%d", total);

the other thing you should be doing is initializing your total to 0 at the outset. In C (and Objective C) intrinsic types aren't zeroed out for you. This is probably affecting your total.

int total = 0;

Edit: some other answers suggest using %i instead. %i and %d are equivalent for string formatting, as is %D. Here's a complete chart of format specifiers:

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html

---

You are using '%@' which is the format used for strings. You need to use '%i' for integers. Example:

NSLog(@"%i", total);

---

- (void)totalIncome:(NSMutableArray *)IncomesArray {
    int i;
    float total;
    for (i = 0; i < [IncomesArray count]; i++)
    {
        Income *income = [IncomesArray objectAtIndex:i];

        total += [[income value] floatValue];
        NSLog(@"%.2f", [[income value] floatValue]);
    }
    self.totalIncomes = [[NSNumber alloc] initWithFloat:(float)total];
    NSLog(@"%.2f", [self.totalIncomes floatValue]);
}

Thanks again for everyones help and fast responses. All my errors were due to my lack of understnding of the importance of using the correct data types at all times.

---

How about:

NSEnumerator *enumerator = [IncomesArray objectEnumerator];

int total = 0; 
Income *income;
while (income = [enumerator nextObject]) {
    total += [income intValue];
    NSLog(@"%d", total);    
}

self.totalIncomes = [NSNumber numberWithInt:total];
NSLog(@"%.2f", self.totalIncomes);

---

A suggested rewrite:

- (void)totalIncome:(NSMutableArray *)IncomesArray {
    float total = 0; //automatics might not be initialized
    for (Income *income in IncomesArray) //use fast enumeration
    {
        total += [[income value] floatValue];
        NSLog(@"%.2f", [[income value] floatValue]);
    }
    //hand an autoreleased object to your setter:
    self.totalIncomes = [NSNumber numberWithFloat:(float)total]; 
    NSLog(@"%.2f", [self.totalIncomes floatValue]);
}