Question

我无法实现四舍五入。

对于theoTimeoutTrick和theoTimeout，这些调用全部返回3.5999999而不是3.6。我如何实现将3.6值转换为NSString AND float vars？

#define minTimeout 1.0
#define defaultNbRetry 5

    float secondsWaitedForAnswer = 20.0;
    float minDelayBetween2Retry = 0.5;

    int theoNbRetries = defaultNbRetry;
    float theoTimeout = 0.0;

    while (theoTimeout < minTimeout && theoNbRetries > 0) {
        theoTimeout = (secondsWaitedForAnswer - (theoNbRetries-1)*minDelayBetween2Retry) / theoNbRetries;
        theoNbRetries--;
    }

    float theoTimeoutTrick = [[NSString stringWithFormat:@"%.1f", theoTimeout] floatValue];
    theoTimeout = roundf(theoTimeout * 10)/10.0;

Answer 1

来自Rounding numbers in Objective-C：

float roundedValue = round(2.0f * number) / 2.0f;
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setMaximumFractionDigits:1];
[formatter setRoundingMode: NSNumberFormatterRoundDown];

NSString *numberString = [formatter stringFromNumber:[NSNumber numberWithFloat:roundedValue]];
[formatter release];

那会给你一个圆形的字符串。你可以把它解析成一个我确定的浮动。

好的，这里有一些测试代码和一些结果：

NSLog(@"%f", round(10*3.56)/10.0);
    =>3.600000
NSLog(@"%f", round(10*3.54)/10.0);
    =>3.500000
NSLog(@"%f", round(10*3.14)/10.0);
    =>3.100000

好的，你知道吗？您的原始代码在我的机器，OSX 10.6和Xcode 4上按预期工作。您究竟如何看到输出？

iPhone - 舍入浮动不起作用

1 个答案: