- 舉個栗子: 計算0.1*999999 看看會有什麼結果?
- (void)testDecimalNumber {
double d1 = 0.01;
double d2 = 999999;
double d3 = d1 * d2;
NSLog(@"%@",n3);
}
結果:
和我們想到的結果:9999.99不同
遇到這種問題解決辦法如下:
- (void)testDecimalNumber {
NSDecimalNumber* n1 = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",d1]];
NSDecimalNumber* n2 = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",d2]];
NSDecimalNumber* n3 = [n1 decimalNumberByMultiplyingBy:n2];
NSLog(@"%@",number);
}
結果:
這次就對了!
可以把float、double轉成NSDecimalNumber類型的對象在計算。可以進行+、-、* 、/ 的運算。
2.用法 四捨五入
-(NSString*)notRounding:(float)price afterPoint:(NSInteger)position
{
NSDecimalNumberHandler* roundingHandler = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundPlain scale:position raiseOnExactness:NO raiseOnOverflow:NO raiseOnUnderflow:NO raiseOnDivideByZero:NO];
NSDecimalNumber* returnNumber;
NSDecimalNumber* ouncesDecimal = [[NSDecimalNumber alloc]initWithFloat:price];
returnNumber = [ouncesDecimal decimalNumberByRoundingAccordingToBehavior:roundingHandler];
return [NSString stringWithFormat:@"%@",returnNumber];
}
測試數據:1.235
結果: