Factorial in Objective C

Welcome to the Factorial in Objective C page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

//
//  factorial.m
//  Factorial in ObjC
//


#import <Foundation/Foundation.h>

int fac(int n) {
    if (n > 1) {
        return fac(n -1) * n;
    }
    else {
        return 1;
    }
}

// Function to convert and validate the input string
// Source: ChatGPT
NSInteger convertAndValidateInput(NSString *inputString) {
    NSScanner *scanner = [NSScanner scannerWithString:inputString];
    NSInteger integerValue = 0;

    // Check if the scanner successfully scanned an integer
    if ([scanner scanInteger:&integerValue] && [scanner isAtEnd]) {
        return integerValue;
    } else {
        // Raise an exception for invalid input
        @throw [NSException exceptionWithName:@"InvalidInputException"
            reason:@"Input is not a valid integer"
            userInfo:nil];
    }
}

int main(int argc, const char * argv[]) {
    NSAutoreleasePool *pool =[[NSAutoreleasePool alloc] init];
    NSString *usage = @"Usage: please input a non-negative integer";
    if (argc < 2) {
        printf("%s\n", [usage UTF8String]);
    }
    else {
        NSString* inputStr = [NSString stringWithUTF8String:argv[1]];
        @try {
            int input = (int)convertAndValidateInput(inputStr);
            if (input < 0) {
                printf("%s\n", [usage UTF8String]);
            }
            else {
                int result = fac(input);
                printf("%d\n", result);
            }
        }
        @catch (NSException *) {
            printf("%s\n", [usage UTF8String]);
        }
    }
    [pool drain];
    return 0;
}

Factorial in Objective C was written by:

• niftycode
• rzuckerm

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

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