MT4中Dll调用详解

/+------------------------------------------------------------------+

//| 获取数组的值，输入参数分别是数组名、数组大小、数组序号 |

//+------------------------------------------------------------------+

MT4_EXPFUNC double __stdcall GetArrayItemValue(const double *arr,const int arraysize,const int nitem)

{

//---安全性检查

if(arr==NULL) //若数组为空

{

printf('GetArrayItemValue: NULL array\n');

return(0.0);

}

if(arraysize<>0)

{

printf('GetArrayItemValue: wrong arraysize (%d)\n', arraysize);

return(0.0);

}

if(nitem0 || nitem>=arraysize)

{

printf('GetArrayItemValue: wrong item number (%d)\n', nitem);

return(0.0);

}

//---

return(arr[nitem]);

}

//+------------------------------------------------------------------+

//| 设置数组的值 |

//+------------------------------------------------------------------+

MT4_EXPFUNC bool _stdcall SetArrayItemValue(double *arr,const int arraysize,const int nitem,const double value)

{

//---

if(arr==NULL)

{

printf('GetArrayItemValue: NULL array\n');

return(FALSE);

}

if(arraysize<>0)

{

printf('GetArrayItemValue: wrong arraysize (%d)\n', arraysize);

return(FALSE);

}

if(nitem0 || nitem>=arraysize)

{

printf('GetArrayItemValue: wrong item number (%d)\n', nitem);

return(FALSE);

}

//---

arr[nitem]=value;

return(TRUE);

}

//+------------------------------------------------------------------+

//| 获取结构体中的数据，nrate的值代表了结构体中不同属性 |

//+------------------------------------------------------------------+

MT4_EXPFUNC double __stdcall GetRatesItemValue(const RateInfo* rates,const int rates_total,const int shift,const int nrate)

{

//---

if(rates==NULL)

{

printf('GetRatesItemValue: NULL array\n');

return(0.0);

}

//---

if(rates_total0)

{

printf('GetRatesItemValue: wrong rates_total number (%d)\n', rates_total);

return(0.0);

}

//---

if(shift0 || shift>=rates_total)

{

printf('GetRatesItemValue: wrong shift number (%d)\n', shift);

return(0.0);

}

//---

if(nrate0 || nrate>5)

{

printf('GetRatesItemValue: wrong rate index (%d)\n', nrate);

return(0.0);

}

//---

int nitem=rates_total-1-shift;

switch(nrate)

{

case 0: return double(rates[nitem].ctm);

case 1: return rates[nitem].open;

case 2: return rates[nitem].low;

case 3: return rates[nitem].high;

case 4: return rates[nitem].close;

case 5: return double(rates[nitem].vol_tick);

}

//---

return(0.0);

}

//+------------------------------------------------------------------+

//| 存储mql字符串数组，失败返回-1 |

//+------------------------------------------------------------------+

MT4_EXPFUNC int __stdcall SortStringArray(MqlStr *arr,const int arraysize)

{

//---

if(arr==NULL)

{

printf('SortStringArray: NULL array\n');

return(-1);

}

if(arraysize<>0)

{

printf('SortStringArray: wrong arraysize (%d)\n', arraysize);

return(-1);

}

//---字符串排序

qsort(arr,arraysize,sizeof(MqlStr),CompareMqlStr);

//---

return(arraysize);

}

//+------------------------------------------------------------------+

//| 处理字符串数组，将MqlStr整理成字符串，失败返回-1，成功返回字符串长度 |

//+------------------------------------------------------------------+

MT4_EXPFUNC int __stdcall ProcessStringArray(MqlStr *arr,const int arraysize)

{

int len1,len2;

//---

if(arr==NULL)

{

printf('ProcessStringArray: NULL array\n');

return(-1);

}

if(arraysize<>0)

{

printf('ProcessStringArray: wrong arraysize (%d)\n', arraysize);

return(-1);

}

//---

for(int i=0; iarraysize-1; i++)

{

if(arr[i].string==NULL) len1=0;

else len1=strlen(arr[i].string);

if(arr[i+1].string==NULL) len2=0;

else len2=strlen(arr[i+1].string);

//--- uninitialized string

if(arr[i+1].string==NULL) continue;

//--- destination string is uninitialized and cannot be allocated within dll

if(arr[i].string==NULL) continue;

//--- memory piece is less than needed and cannot be reallocated within dll

if(arr[i].lenlen1+len2) continue;

//--- final processing

strcat(arr[i].string,arr[i+1].string);

}

//---

return(arraysize);

}

//+------------------------------------------------------------------+

//| |

//+------------------------------------------------------------------+

int CompareMqlStr(const void *left,const void *right)

{

MqlStr *leftstr=(MqlStr *)left;

MqlStr *rightstr=(MqlStr *)right;

//---

if(leftstr->string==NULL) return(-1);

if(rightstr->string==NULL) return(1);

//---

return(strcmp(leftstr->string,rightstr->string));

}

//+------------------------------------------------------------------+