View import table of pe in C

#include<windows.h>
#include<stdio.h>
#include<dbghelp.h>

DWORD get_thunk(PIMAGE_IMPORT_DESCRIPTOR im)
{
    if(im->OriginalFirstThunk==0)
    return im->FirstThunk;
    else
    return im->OriginalFirstThunk;
}

int main(int i,char *a[])
{
    HANDLE file,file_map;
    LPVOID base;
    PIMAGE_DOS_HEADER dos;
    PIMAGE_NT_HEADERS nt;
    PIMAGE_SECTION_HEADER sec;
    PIMAGE_IMPORT_DESCRIPTOR import;
    PIMAGE_THUNK_DATA thunk;
    PIMAGE_IMPORT_BY_NAME f;
    LPSTR dll_name,func_name;


    if(i!=2)
    {
        printf("Usage: %s <PE>\n",a[0]);
        return 0;
    }

    file=CreateFileA(a[1],GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);
    if(file==NULL)
    {
        printf("Failed to open file");
        return 0;
    }

    file_map=CreateFileMappingA(file,NULL,PAGE_READONLY,0,0,NULL);
    if(file_map==NULL)
    {
        printf("CreateFileMappingA() Failed");
        return 0;
    }

    base=MapViewOfFile(file_map,FILE_MAP_READ,0,0,0);
    if(base==NULL)
    {
        printf("MapViewOfFile() Failed");
        return 0;
    }

    dos=(PIMAGE_DOS_HEADER)base;
    if(dos->e_magic!=23117)
    {
        printf("Invalid PE");
        return 0;
    }

    nt=base+dos->e_lfanew;

    if(nt->Signature!=IMAGE_NT_SIGNATURE)
    {
        printf("Invalid PE");
        return 0;
    }

    if(nt->OptionalHeader.Magic!=IMAGE_NT_OPTIONAL_HDR64_MAGIC) //for 32bit , use IMAGE_NT_OPTIONAL_HDR32_MAGIC
    {
        printf("This is not 64 bit PE");
        return 0;
    }

    sec=(PIMAGE_SECTION_HEADER)((LPVOID)nt+24+nt->FileHeader.SizeOfOptionalHeader); //this is use less. I just showed how to enter section header

    if(nt->OptionalHeader.DataDirectory[1].VirtualAddress==0)
    {
        printf("There is no import table in this PE");
        return 0;
    }

    import=(PIMAGE_IMPORT_DESCRIPTOR)ImageRvaToVa(nt,base,nt->OptionalHeader.DataDirectory[1].VirtualAddress,NULL);

    while(import->Name!=0)
    {
        dll_name=(LPSTR)ImageRvaToVa(nt,base,import->Name,NULL);
        printf("\t\tDll Name: %s\n",dll_name);
        thunk=(PIMAGE_THUNK_DATA)ImageRvaToVa(nt,base,get_thunk(import),NULL);
        i=0;
        while(thunk->u1.AddressOfData!=0)
        {
            i++;
            if(thunk->u1.Ordinal & IMAGE_ORDINAL_FLAG)
            {
                printf("%d. Unknown Function - Function ordinal: %#x\n",i,IMAGE_ORDINAL(thunk->u1.Ordinal));
            }
            else
            {
                f=(PIMAGE_IMPORT_BY_NAME)ImageRvaToVa(nt,base,thunk->u1.AddressOfData,NULL);
                func_name=(LPSTR)f->Name;
                printf("%d. %s\n",i,func_name);
            }
            thunk++;
        }
        import++;
    }

    return 0;
}