Question

该程序应该执行一系列分数的sigma，并显示结果。但是，它只输出0.000000。根据其他人的建议，看起来剩余部分被整数算术截断，但我无法找到。有什么想法吗？：

#import <Foundation/Foundation.h>

// The Fraction class

@interface Fraction : NSObject

{
    int numerator;
    int denominator;
}

@property int numerator, denominator;

-(void) print;
-(void) setTo: (int) n over: (int) d;
-(double) convertToNum;
-(void) reduce;
-(Fraction *) add: (Fraction *) f;


@end

---------------------------------------


#import "Fraction.h"


@implementation Fraction

@synthesize numerator, denominator;

-(void) print

{
    NSLog (@"%i/%i", numerator, denominator);
}

-(double) convertToNum
{
    if (denominator != 0) 
        return ((double) numerator / (double) denominator);
    else 
        return 1.0;
}

-(void) setTo: (int) n over: (int) d
{
    numerator = n;
    denominator = d;
}


-(void) reduce

{
    int u = numerator;
    int v = denominator;
    int temp;

    while (v != 0) {
        temp = v % u;
        u = v;
        v = temp;
    }

    numerator /= u;
    denominator /= u;
}


-(Fraction *) add: (Fraction *) f

{

    Fraction *result = [[Fraction alloc] init];
    int resultNum, resultDenom;

    resultNum = numerator * f.denominator + 
    denominator * f.numerator;
    resultDenom = denominator * f.denominator;

    [result setTo: resultNum over: resultDenom];

    [result reduce];
    return result;
}


@end


-------------------------------------------------------

#import "Fraction.h"

int main (int argc, char *argv[])
{

    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; 

    Fraction *aFraction = [[Fraction alloc] init]; 
    Fraction *sum = [[Fraction alloc] init], *sum2; 
    int i, pow2, n;

    // set 1stfraction to 0 

    [sum setTo: 0.0 over: 1.0];



    NSLog (@"Enter your value for n:");
    scanf ("%i", &n);


    pow2 = 2.0; 
    for (i = 1; i <= n; ++i) {
        [aFraction setTo: 1 over: pow2]; 
        sum2 = [sum add: aFraction]; 
        [sum release];  // release previous sum 
        sum = sum2; 
        pow2 *= 2.0;


    }

    NSLog (@"After %i iterations, the sum is %f", n, [sum convertToNum]);
    [aFraction release];
    [sum release];




    [pool drain];
    return 0;
}

Answer 1

解决：

- （void）reduce

{ int u = numerator; int v =分母; int temp;

while (v != 0) {
    temp = u % v;            // 'u' and 'v' were transposed.
    u = v;
    v = temp;
}

来自Kochan文本的Obj-C程序表现不尽如人意

1 个答案: