iOS NSDecimalNumber 货币计算 四舍五入

今天遇到一个问题 服务器返回货币数据 妈的 用string 》 floatvalue   不准确

去百度查查 妈的国人分享精神真差  真他妈的自私 一个破壁文章没几个字 还是从国外翻译过来的 全他妈转发 很不详细

弄明白就不能 再出一个完整点的 都是从菜鸟过来的 尼玛

今天去国外查完 分享下

／／貌似 格式化的帮手 妈的 我英语高考61分 我咋知道它叫啥

NSDecimalNumberHandler *roundUp = [NSDecimalNumberHandler

decimalNumberHandlerWithRoundingMode:NSRoundBankers

scale:2

raiseOnExactness:NO

raiseOnOverflow:NO

raiseOnUnderflow:NO

raiseOnDivideByZero:YES];

枚举

NSRoundPlain,   // Round up on a tie ／／貌似取整 翻译出来是个圆 吗的垃圾百度翻译

NSRoundDown,    // Always down == truncate  ／／只舍不入

NSRoundUp,      // Always up    ／／ 只入不舍

NSRoundBankers  // on a tie round so last digit is even  貌似四舍五入

//90.7049+0.22 然后四舍五入

NSDecimalNumber *subtotal = [NSDecimalNumberdecimalNumberWithString:@"90.7049"];

NSDecimalNumber *discount = [NSDecimalNumberdecimalNumberWithString:@"0.22"];

NSDecimalNumber *total = [subtotal decimalNumberByAdding:discount withBehavior:roundUp];

NSLog(@"Rounded total: %@", total);

／／另一个方法  不准 推荐不用 国内网站一个煞笔 告诉我们的

NSLog(@"%f", round([[NSStringstringWithFormat:@"%f",12345.6749] floatValue]*100)/100);

NSDecimalNumber 其他用法

所有NSDecimalNumber对象是不可变的，这意味着已经被创建后不能改变它们的值。

NSDecimalNumber*price;

price = [NSDecimalNumberdecimalNumberWithMantissa:1599

exponent:-2   ／／10的－2次方

isNegative:NO];

等效

price = [NSDecimalNumberdecimalNumberWithString:@"15.99"];

NSDecimalNumber*price1 = [NSDecimalNumberdecimalNumberWithString:@"15.99"];

NSDecimalNumber*price2 = [NSDecimalNumberdecimalNumberWithString:@"29.99"];

NSDecimalNumber*coupon = [NSDecimalNumberdecimalNumberWithString:@"5.00"];

NSDecimalNumber*discount = [NSDecimalNumberdecimalNumberWithString:@".90"];

NSDecimalNumber*numProducts = [NSDecimalNumberdecimalNumberWithString:@"2.0"];

NSDecimalNumber *subtotal = [price1 decimalNumberByAdding:price2];

NSDecimalNumber *afterCoupon = [subtotal decimalNumberBySubtracting:coupon];

NSDecimalNumber *afterDiscount = [afterCoupon decimalNumberByMultiplyingBy:discount];

NSDecimalNumber *average = [afterDiscount decimalNumberByDividingBy:numProducts];

NSDecimalNumber*averageSquared = [average decimalNumberByRaisingToPower:2];

的NSLog（@“小计：％@”，加后）;/ / 45.98

的NSLog（@“优惠券后：％@”，减）;/ / 40.98

的NSLog（（@“折后：％@”），9/10）;/ / 36.882

的NSLog（@“每股平均价产品：％@”，平均）;/ / 18.441

的NSLog（@“平均价的平方：％@”，averageSquared）;/ / 340.070481

//保留小数点后两位

NSDecimalNumberHandler*roundUp = [NSDecimalNumberHandler

decimalNumberHandlerWithRoundingMode:NSRoundUp

scale:2

raiseOnExactness:NO

raiseOnOverflow:NO

raiseOnUnderflow:NO

raiseOnDivideByZero:YES];

//9折后 36.882 有余进位结果 36.89

NSDecimalNumber*subtotal = [NSDecimalNumberdecimalNumberWithString:@"40.98"];

NSDecimalNumber*discount = [NSDecimalNumberdecimalNumberWithString:@".90"];

NSDecimalNumber*total = [subtotal decimalNumberByMultiplyingBy:discount

withBehavior:roundUp];

NSLog(@"Rounded total: %@", total);

//比较大小

NSDecimalNumber*discount1 = [NSDecimalNumberdecimalNumberWithString:@".85"];

NSDecimalNumber*discount2 = [NSDecimalNumberdecimalNumberWithString:@".9"];

NSComparisonResult result = [discount1 compare:discount2];

if (result ==NSOrderedAscending) {

NSLog(@"85%% < 90%%小于");

} else if (result == NSOrderedSame) {

NSLog(@"85%% == 90%%等于");

} elseif (result ==NSOrderedDescending) {

NSLog(@"85%% > 90%%大于");

}