Double up

Possible Duplicate: long double vs double I am unable to understand the difference between between long double and double in C and C++. Can anyone help? C语言中，float和double都属于浮点数。区别在于：double所表示的范围，整数部分范围大于float，小数部分，精度也高于float。举个例子：圆周率 3.1415926535 这个数字，如果用float来表示，最多只能精确到小数点后面的6位。而double大约能精确到小数点后面的15位左右。具体精确到几位，跟所用的编译器. En double se pueden almacenar números más grandes y también más decimales. Con los números que has probado no se ve diferencia porque cout redondea la representación interna para mostrar pocos decimales, y lo que ves en ambos casos es lo mismo, pero internamente no son iguales. A double has a much higher precision due to it's difference in size. If the numbers you are using will commonly exceed the value of a float, then use a double. Several other people have mentioned performance isssues. That would be exactly last on my list of considerations. Correctness should be your 1 consideration. The long double function prototypes are identical to the prototypes for their double counterparts, except that the longdouble data type replaces the double data type. The long double versions of these functions should not be used in new code. double** 是指向 double* 类型的指针类型。区别不是很显然的吗？ double [5] 类型能隐式转换成 double* 类型，但它们不是同一类型。可以考虑一下 short 和 long 这两种类型是能相互隐式转换的，但它们显然没有因此变成同一类型。 Your variant is as correct as it ever gets. %lf is the correct format specifier for double. But it became so in C99. Before that one had to use %f. In my earlier question I was printing a double using cout that got rounded when I wasn't expecting it. How can I make cout print a double using full precision? float e double são mais rápidos, eficientes e econômicos do que os BigDecimal s do Java; não posso afirmar muito sobre o Decimal do C , mas creio que para multiplicação seja muito mais leve. Normalmente, nos processadores mais modernos, existe um núcleo de processamento de aritmética de ponto flutuante. I've read about the difference between double precision and single precision. However, in most cases, float and double seem to be interchangeable, i.e. using one or the other does not seem to affec.

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