对数组求和 - Objective-C [英] Sum an Array - Objective-C

问题描述

我刚刚开始，我正在寻找一种简单的方法来总结一个简单的数组.我已经阅读了关于键值编码的苹果开发者网站，但我不明白如何将它应用到我的数组中，或者这是否是求和的合适方法.

I'm just starting out and I'm looking for an easy way to sum a simple array. I've read into apple developer site on key value coding and I don't understand how to apply that to my array or if that's the appropriate way to sum this.

我使用键值编码的绊脚石是 .keypathToProperty - 我可以理解您需要在二维数组中进一步引用，但它们不显示数组代码，只显示行标题的键路径所以我还想不通.

My stumbling block with the key value coding is the .keypathToProperty - I can sort of understand that you need a further reference in a 2D array but they don't show the array code, only the keypath to the title of the row so I can't figure it out yet.

NSMutableArray *numArray = [NSMutableArray arrayWithCapacity:4];
    [numArray addObject:num1];
    [numArray addObject:num2];  
    [numArray addObject:num3];
    [numArray addObject:num4];

感谢您的回复！

谢谢

格雷厄姆

推荐答案

自动执行的方法是:

NSNumber * sum = [numArray valueForKeyPath:@"@sum.self"];

但如果您刚刚开始，我建议您避免使用集合键路径运算符并采用更简单的方法:

But if you're just starting out, I would recommend avoiding the collection key-path operators and go for the more simple way:

double sum = 0;
for (NSNumber * n in numArray) {
  sum += [n doubleValue];
}

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