Converting a octal String to Decimal in Objective-C?

Question

I trying to do conversions between Binary, Octal, Decimal and Hexadecimal in Objective-C. I had problems converting Octal to Decimal.

I have tried the following:

NSString *decString = [NSString stringWithFormat:@"%d", 077];

It works fine, returning 63 as expected, but my Octal value is a NSString. How can I tell the computer that it is a Octal;

I know there is a method called "scanHexInt:" which I used to convert Hexadecimal to decimal, but it seems there is no scanOctInt...

Any help would be appreciated!

Look over there : http://stackoverflow.com/questions/6647787/how-to-convert-decimal-into-octal-in-objective-c — rdurand, Oct 10 '12 at 11:33
@rdurand But how does this help to convert an octal NSString into an int? — nullp01nter, Oct 10 '12 at 11:58

mvds · Accepted Answer · 2012-10-10T14:32:37.863

4

The cleanest solution is probably:

long result = strtol(input.UTF8String, NULL, 8);

or

long long result = strtoll(input.UTF8String, NULL, 8);

edited Oct 10 '12 at 14:32

answered Oct 10 '12 at 13:34

mvds

45,755
8
102
111

I like this answer even better than mine XD +1 – borrrden Oct 10 '12 at 13:56
This is exactly what I need! But there is a little problem, if the value is larger than 10,000,000,000, it went wrong. I've already defined result as unsigned long long int. – Keoros Oct 10 '12 at 14:17

nullp01nter · Answer 2 · 2012-10-10T11:55:51.413

Define a category on NSString (put this on top of any of your source code modules or into a new .m/.h file pair, @interface goes into .h, @implementation into .m):

@interface NSString (NSStringWithOctal)
-(int)octalIntValue;
@end

@implementation NSString (NSStringWithOctal)
-(int)octalIntValue
{
    int iResult = 0, iBase = 1;
    char c;

    for(int i=(int)[self length]-1; i>=0; i--)
    {
        c = [self characterAtIndex:i];
        if((c<'0')||(c>'7')) return 0;
        iResult += (c - '0') * iBase;
        iBase *= 8; 
    }
    return iResult;
}
@end

Use it like that:

NSString *s = @"77";
int i = [s octalIntValue];
NSLog(@"%d", i);

The method returns an integer representing the octal value in the string. It returns 0, if the string is not an octal number. Leading zeroes are allowed, but not necessary.

It works, but it dosen't work well in a for circulation. Thanks anyway. — Keoros, Oct 10 '12 at 15:04

score 0 · Answer 3 · answered Oct 10 '12 at 13:20

0

Alternatively, if you want to drop down to C, you can use sscanf

int oct;
sscanf( [yourString UTF8String], "%o", &oct );

answered Oct 10 '12 at 13:20

borrrden

33,256
8
74
109

Converting a octal String to Decimal in Objective-C?

3 Answers3

Linked