Trunc

基本解釋

Trunc: Truncates a real number to an integer.
實(shí)數(shù)截尾為整型數(shù)，肯定會(huì)存在誤差的。
When we specify a format as an input to the ROUND and TRUNC functions, things become a bit more involved, but the concepts of rounding and truncating still remain the same.
因?yàn)闀r(shí)間已經(jīng)超過(guò)中午的12點(diǎn)，距離第二天的時(shí)間比距離當(dāng)天起始時(shí)間要近，所以Round函數(shù)返回第二天的起始時(shí)間，但是Trunc函數(shù)依然返回輸入時(shí)間的起始部分，這一點(diǎn)和對(duì)小數(shù)進(jìn)行四舍五入和截取相似。
SELECT TRUNC(7.7788,2) FROM DUAL; 249. COUNT
計(jì)算滿足條件的記錄數(shù).
ofstream ofile("D:\\v.txt", ios_base::binaryios_base::trunc);
我需要的是二進(jìn)制的不是這種明文的！