指针和固定大小的缓冲区只能在不安全的上下文中使用
本文关键字:不安全 上下文 缓冲区 指针 | 更新日期: 2023-09-27 18:31:58
我在一个类中有 2 个函数,并且在调用 ParseBits() 函数时出错,即"int num_elements = ParseBits(bits, buffer);
",因为我传递了"public int ParseBits(string bits, int* buffer)
"的"缓冲区"参数:
功能1:
public float AssignFitness(string bits, int target_value)
{
//holds decimal values of gene sequence
int[] buffer = new int[(VM_Placement.AlgorithmParameters.chromo_length / VM_Placement.AlgorithmParameters.gene_length)];
int num_elements = ParseBits(bits, buffer);
// ok, we have a buffer filled with valid values of: operator - number - operator - number..
// now we calculate what this represents.
float result = 0.0f;
for (int i=0; i < num_elements-1; i+=2)
{
switch (buffer[i])
{
case 10:
result += buffer[i+1];
break;
case 11:
result -= buffer[i+1];
break;
case 12:
result *= buffer[i+1];
break;
case 13:
result /= buffer[i+1];
break;
}//end switch
}
// Now we calculate the fitness. First check to see if a solution has been found
// and assign an arbitarily high fitness score if this is so.
if (result == (float)target_value)
return 999.0f;
else
return 1/(float)fabs((double)(target_value - result));
// return result;
}
功能2:
public int ParseBits(string bits, int* buffer)
{
//counter for buffer position
int cBuff = 0;
// step through bits a gene at a time until end and store decimal values
// of valid operators and numbers. Don't forget we are looking for operator -
// number - operator - number and so on... We ignore the unused genes 1111
// and 1110
//flag to determine if we are looking for an operator or a number
bool bOperator = true;
//storage for decimal value of currently tested gene
int this_gene = 0;
for (int i = 0; i < VM_Placement.AlgorithmParameters.chromo_length; i += VM_Placement.AlgorithmParameters.gene_length)
{
//convert the current gene to decimal
this_gene = BinToDec(bits.Substring(i, VM_Placement.AlgorithmParameters.gene_length));
//find a gene which represents an operator
if (bOperator)
{
if ((this_gene < 10) || (this_gene > 13))
continue;
else
{
bOperator = false;
buffer[cBuff++] = this_gene;
continue;
}
}
//find a gene which represents a number
else
{
if (this_gene > 9)
continue;
else
{
bOperator = true;
buffer[cBuff++] = this_gene;
continue;
}
}
}//next gene
// now we have to run through buffer to see if a possible divide by zero
// is included and delete it. (ie a '/' followed by a '0'). We take an easy
// way out here and just change the '/' to a '+'. This will not effect the
// evolution of the solution
for (int i = 0; i < cBuff; i++)
{
if ((buffer[i] == 13) && (buffer[i + 1] == 0))
buffer[i] = 10;
}
return cBuff;
}
我在突出显示的行上收到此函数的 2 个错误:
Error 1: The best overloaded method match for 'VM_Placement.Program.ParseBits(string, int*)' has some invalid arguments
Error 2: Pointers and fixed size buffers may only be used in an unsafe context
您需要在 unsafe
块中使用原始指针将函数括起来。
unsafe
{
//your code
}
我遇到了同样的问题,但这里的任何其他答案都没有解决。我不断收到不同的错误。
无论函数使用不安全代码,都需要使用"unsafe"关键字进行声明。
例如:
static unsafe void myFunction(int* myInt, float* myFloat)
{
// Function definition
}
就个人而言,我在制作包装类时试图这样做。
对于那些感兴趣的人,它最终看起来像这样:
using System.Runtime.InteropServices;
namespace myNamespace
{
public class myClass
{
[DllImport("myLib.so", EntryPoint = "myFunction")]
public static extern unsafe void myFunction(float* var1, float* var2);
}
}
MSDN"不安全代码教程"中有很多很棒的信息:
https://msdn.microsoft.com/en-us/library/aa288474(v=vs.71).aspx
它可能值得一读,我发现它非常有用。
也许我错过了,但你似乎没有做任何实际需要使用int*
的事情。为什么不简单地给它传递一个 int 数组并将 ParseBits 函数签名更改为:
public int ParseBits(string bits, int[] buffer)
并完全移除unsafe{ ... }
块。