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
NSDecimalNumberHandler *roundUp = [NSDecimalNumberHandler
decimalNumberHandlerWithRoundingMode:NSRoundBankers
scale:2
raiseOnExactness:NO
raiseOnOverflow:NO
raiseOnUnderflow:NO
raiseOnDivideByZero:YES];
枚举
NSRoundPlain, // Round up on a tie //四舍五入
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
//if(四舍五入位 == 5)(四舍五入位(5)+ 保留位 )%2 == 0 ? 入 : 舍 ;
if(四舍五入位 != 5) 遵从四舍五入
//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
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];
参数 说明 roundingMode 要使用的舍入模式,有四种值: NSRoundUp, NSRoundDown, NSRoundPlain, and NSRoundBankers scale 结果保留几位小数 raiseOnExactness 发生精确错误时是否抛出异常,一般为NO raiseOnOverflow 发生溢出错误时是否抛出异常,一般为NO raiseOnUnderflow 发生不足错误时是否抛出异常,一般为NO raiseOnDivideByZero 被0除时是否抛出异常,一般为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");
}