How to save image files (.jpg) with different names within a loop?

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Hello,

I'm trying to save files with different names within a loop in C++, I've found a number of solutions, but unfortunately it doesn't fit my work.
My function saves a QRcode as an image (.jpg). the syntax of the statement which does the saving is as follows:

C++

ERRCODE _stdcall BCSaveImageA  ( t_BarCode *  pBarCode,  
  LPCSTR  lpszFileName,  
  e_IMType  eImageType,  
  LONG  lXSize,  
  LONG  lYSize,  
  DOUBLE  dXRes,  
  DOUBLE  dYRes  
 )

where:

Parameters:
[in] pBarCode Pointer to barcode structure.
[in] lpszFileName Filename
[in] eImageType Enumeration for the type of the image.
[in] lXSize X-Size of the image [pixel]. For Vector-EPS the unit is [0.001 mms]
[in] lYSize Y-Size of the image [pixel]. For Vector-EPS the unit is [0.001 mms]
[in] dXRes X-Resolution of the image [pixels / inch].
[in] dYRes Y-Resolution of the image [pixels / inch].

which is used successfully to generate a single file in my program as follows:

C++

eCode = BCSaveImageA(pBC,"C://webcontent/QR12.jpg", 4, LBarcodeWidth,LBarcodeHieght, dpi, dpi);

The problem is how can I save a number of image files (.jpg) with different names? I've used a for loop and tried to write the name of the new file in the above statement as follows:

C++

eCode = BCSaveImageA(pBC,"C://webcontent/QR"+IntToStr(i)+".jpg", 4, LBarcodeWidth,LBarcodeHieght, dpi, dpi);

where IntToStr is a function that converts int to string

C++

string IntToStr(int n) 
{
    stringstream result;
    result << n;
    return result.str();
}

Thank you & Best Regards.
Rania

Posted 28-Jan-15 10:13am

raniam

Updated 28-Jan-15 10:19am

Tomas Takac

v2

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BacchusBeale · Answer 1 · 2015-01-28T12:45:00

the loop looks OK, but can't see other code.

one mistake is the filename needs LPCSTR which is a C style string so to convert the C++ string you'd need

C++

str.c_str()

second mistake is concatenation with + works with string but not C strings.
so one idea is to adapt method:

string IntToStr(int n) 
{
    stringstream result;
    result<< "C://webcontent/QR"<<n<<".jpg";
    return result.str();
}

then convert string to

LPCSTR

User 59241 · Answer 2 · 2015-01-28T16:53:00

Your question is really about constructing a LPCSTR.

Try the following

C++

#include<string>
using namespace std;

C#

for(int n = 0; n < 20; n++)
{
        string filename = "C://webcontent/QR"+ to_string((_ULonglong)n) +".jpg";
        eCode = BCSaveImageA(pBC, filename.c_str(), 4, LBarcodeWidth,LBarcodeHieght, dpi, dpi);
}

If your compiler is C++11 compliant you wont need the _ULonglong cast.

How to save image files (.jpg) with different names within a loop?

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