char* string; 与 char string; 有何区别？
char pBeginPage = "";
char pEndPage = "";
itoa(aBeginPage, pBeginPage, 10);
itoa(aEndPage, pEndPage, 10);
pBeginPage 和 pEndPage 可以声明为 char * 类型吗？
Chapter 1 Hello, ATL
Source Code: www.sellsbrothers.com/writing/atlbook
PARIS (AFP) –
A French software engineer
said on Friday he was claiming a world record for calculating Pi, the
constant that has fascinated mathematicians for millennia.
told AFP he used an inexpensive desktop computer -- and not a
supercomputer used in past records -- to calculate Pi to nearly 2.7
trillion decimal places.
That is around 123 billion digits more than the previous record set last August by Japanese professor Daisuke Takahashi, he said.
Takahashi, using a T2K Open Supercomputer, took 29 hours to crunch Pi to 2.577 billion digits.
Bellard took 131 days, comprising 103 for the computation in binary
digits, 13 days for verification, 12 days to convert the binary digits
to a base of 10 and three final days to check the conversion.
The gear cost "a bit less than 2,000 euros" (3,000 dollars), Bellard, who earns a living as a software consultant in digital television in Paris, said in an email exchange.
"It is a completely standard PC. The only unusual thing is that it has five 1.5-teraoctet hard disks. Mainstream PCs generally have only one 1-teraoctet disk."
Bellard has placed on his website details of the achievement, including
the use of a high-powered mathematical engine called the Chudnovsky
algorithm that chewed through the computation.
Extracts of the 2,699,999,990,000-digit outcome have been published so
that they can be compared to preceding records in order to gain
independent verification, Bellard told AFP.
Files containing the digits are also being offered to any outside organism keen on hosting the record, he said.
Pi, the ratio of a circle's circumference to its diameter, kicks off
with 3.14159... in a string whose digits are believed never to repeat
Bellard said he was "not especially interested" in Pi's digits but more
in taking up the gauntlet of writing the software to carry out the
"Optimising these algorithms to get good performance is a difficult programming challenge," he wrote.
To improve my writing ability, I want to write blog every day!
Today I recognize one important thing:
You must research the code to improve your programming level, not search in Google!
From now on, I should not find information as soon as I encounter a problem. I will research all the information I have first! I can review my codes first, I can read my books first; I can research my documents and papers first. After all of these, I google my problem then.