[英]C++ unix 32bit to Red Hat Linux running on an x86_64 chip (64-bit server)
I am working on a project that is porting application in C++ from 32 bit unix to Red Hat Linux running on an x86_64 chip (64-bit server). 我正在一个项目中,该项目将C ++中的应用程序从32位Unix移植到在x86_64芯片(64位服务器)上运行的Red Hat Linux。 I am facing issues related to long data types.I wrote a sample program to print a binary long and unsigned long value of 1. This has an extra 1 in middle:
我遇到了与长数据类型有关的问题。我编写了一个示例程序来打印二进制long和无符号long值1。中间有一个额外的1:
ul = 0000000000000000000000000000000100000000000000000000000000000001 ul = 0000000000000000000000000000000000000100000000000000000000000000000001
l = 0000000000000000000000000000000100000000000000000000000000000001 l = 0000000000000000000000000000000000000100000000000000000000000000000000000001
string binary(unsigned long i)
{
int n = sizeof(unsigned long);
string s;
n *= 8;
--n;
while (n >= 0)
{
unsigned long mask = (1 << n);
s += (mask & i ? "1" : "0");
--n;
}
return s;
}
string binary(long i)
{
int n = sizeof( long);
string s;
n *= 8;
--n;
while (n >= 0)
{
long mask = (1 << n);
s += (mask & i ? "1" : "0");
--n;
}
return s;
}
int main()
{
unsigned long ul = 1;
long l = 1;
cout << "sizeof ul = " << sizeof ul << ", ul = " <<ul<< endl;
cout << "sizeof l = " << sizeof l << ", l = " << l << endl;
cout << "ul = " << binary(ul) << endl;
cout << "l = " << binary(l) << endl;
return 0;
}
As you all can see I am not getting why there is an extra 1 IN MIDDLE. 大家都知道,我不明白为什么要多加1英寸中间价。 This is causing run time issues in my application.
这在我的应用程序中导致运行时问题。 Please let me know.
请告诉我。 I am getting extra 1 middle in Red Hat Linux running on an x86_64 chip (64-bit server) not in unix and that is the cause of run time issues.
我在x86_64芯片(64位服务器)上而不是在unix上运行的Red Hat Linux中得到了额外的1分,这是运行时问题的原因。 Any idea please let me know.
有什么想法请告诉我。
The problem is here: 问题在这里:
unsigned long mask = (1 << n);
Apparently, a unsigned long
has 8 byte and a normal int
has 4 byte on your system. 显然,在您的系统上,
unsigned long
有8个字节,而普通int
有4个字节。
Here you have a int
with value 1 (every literal value is int
if nothing else is explicitely specified). 这里有一个
int
值为1(每字面值为int
如果没有其他明确地规定)。 You´re doing the shifting on this 4 byte int
, and then the result is converted to 8 byte to save it in mask
. 您正在对此4字节
int
进行移位, 然后将结果转换为8字节以将其保存在mask
。 Shifting more than 31 bit is too much in 4 byte, yet you´re doing it until 63 bit. 在4字节中移出超过31位是太多了,但是直到63位为止。
To solve the problem, you have to tell the compiler that 1
is meant a 8 byte unsigned long
. 要解决该问题,您必须告诉编译器
1
表示8字节unsigned long
。
Three possibilites: 三种可能性:
unsigned long mask = (1UL << n);
//or
unsigned long mask = ((unsigned long)1 << n);
//or just
unsigned long mask = 1;
mask = mask << n;
The other function (for the signed type) has the same problem. 另一个函数(用于带符号的类型)具有相同的问题。
With the first variant, use just L
there, without U
. 对于第一个变体,在那里只使用
L
,而没有U
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