hello group,

i'm tyrying to call into  a C Dlls and unable to get the results properly
after getting executed the functions.

I'm providing with all the code part:

C API function :

int PBFNGetZipList(
char *zipExpr,
int count,
pDbxSearchDataDef *returnData);

• zipExpr: The ZIP code search criteria can be any one to five-digit number.
For
example, 605 returns all ZIP codes starting with 605 including 60515, 60516.
In
another example, 60 returns all ZIP codes beginning with 60.
• count: The maximum number of results to be returned.
• returnData: returnData is a pointer to a data structure of type
dbxSearchDataDef.

Returns a list of ZIP codes (i.e., 60501, 60504, 60599) that match the
search criteria.

The dbxSearchDataDef C structure contains return address information. The
dbxSearchDataDef structure is shown next.
typedef struct dbxSearchDataDefinition
{
char zipcode[6];
char cityName[29];
char countyName[26];
char stateAbbreviation[3];
} dbxSearchDataDef, * pDbxSearchDataDef;

My C# code here:

API function prototype declaration in C#

[DllImport("PBFN",CharSet=CharSet.Ansi)]
public static extern int PBFNGetZipList(
[MarshalAs(UnmanagedType.LPTStr)]
StringBuilder zipExpr,
int count,
ref PBFNSearchDataDefinition returnData1);

structure definition:

[ StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
public struct PBFNSearchDataDefinition
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=6)]
    public String zipcode;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=29)]
    public String cityName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=26)]
    public String countyName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=3)]
    public String stateAbbreviation;
}

Calling the function:

StringBuilder zip = new StringBuilder();
zip.Append("605");
int count= 2;
int getcity = 0;

getcity = PBFNGetZipList(zip,count,ref searchcities);

getcity should return the value with the data updated to the structure
searchcities.

I tried with different options like stringbuilder,String type , but couldn't
find exact solution. Can any one tell me What

the changes i have to make in my code.

Thanks in Advance.

Regards,
kittu.