Suppress system() output - c++

Question

First off, I do mostly C#, .Net development so go easy on me if this is a stupid question.
I am implementing an Ericcson open source project to convert an image to another format. The problem is that on conversion an output to a console happens as follows...
1 file(s) copied.
I need to suppress this dialog that pops up. I just want to execute the system command with no output. I think I have isolated the area of the code causing this.
void writeOutputFile(char *dstfile, uint8* img, uint8* alphaimg, int width, int height)
{
char str[300];
if(format!=ETC2PACKAGE_R_NO_MIPMAPS&&format!=ETC2PACKAGE_RG_NO_MIPMAPS)
{
fWritePPM("tmp.ppm",width,height,img,8,false);
//PRINTF("Saved file tmp.ppm \n\n");
}
else if(format==ETC2PACKAGE_RG_NO_MIPMAPS)
{
fWritePPM("tmp.ppm",width,height,img,16,false);
}
if(format==ETC2PACKAGE_RGBA_NO_MIPMAPS||format==ETC2PACKAGE_RGBA1_NO_MIPMAPS||format==ETC2PACKAGE_sRGBA_NO_MIPMAPS||format==ETC2PACKAGE_sRGBA1_NO_MIPMAPS)
fWritePGM("alphaout.pgm",width,height,alphaimg,false,8);
if(format==ETC2PACKAGE_R_NO_MIPMAPS)
fWritePGM("alphaout.pgm",width,height,alphaimg,false,16);
// Delete destination file if it exists
if(fileExist(dstfile))
{
sprintf(str, "del %s\n",dstfile);
system(str);
}
int q = find_pos_of_extension(dstfile);
if(!strcmp(&dstfile[q],".ppm")&&format!=ETC2PACKAGE_R_NO_MIPMAPS)
{
// Already a .ppm file. Just rename.
sprintf(str,"move tmp.ppm %s\n",dstfile);
//PRINTF("Renaming destination file to %s\n",dstfile);
}
else
{
// Converting from .ppm to other file format
//
// Use your favorite command line image converter program,
// for instance Image Magick. Just make sure the syntax can
// be written as below:
//
// C:\imconv source.ppm dest.jpg
//
if(format==ETC2PACKAGE_RGBA_NO_MIPMAPS||format==ETC2PACKAGE_RGBA1_NO_MIPMAPS||format==ETC2PACKAGE_sRGBA_NO_MIPMAPS||format==ETC2PACKAGE_sRGBA1_NO_MIPMAPS)
{
// Somewhere after version 6.7.1-2 of ImageMagick the following command gives the wrong result due to a bug.
// sprintf(str,"composite -compose CopyOpacity alphaout.pgm tmp.ppm %s\n",dstfile);
// Instead we read the file and write a tga.
//PRINTF("Converting destination file from .ppm/.pgm to %s with alpha\n",dstfile);
int rw, rh;
unsigned char *pixelsRGB;
unsigned char *pixelsA;
fReadPPM("tmp.ppm", rw, rh, pixelsRGB, 8);
fReadPGM("alphaout.pgm", rw, rh, pixelsA, 8);
fWriteTGAfromRGBandA(dstfile, rw, rh, pixelsRGB, pixelsA, true);
free(pixelsRGB);
free(pixelsA);
sprintf(str,""); // Nothing to execute.
}
else if(format==ETC2PACKAGE_R_NO_MIPMAPS)
{
sprintf(str,"imconv alphaout.pgm %s\n",dstfile);
//PRINTF("Converting destination file from .pgm to %s\n",dstfile);
}
else
{
sprintf(str,"imconv tmp.ppm %s\n",dstfile);
//PRINTF("Converting destination file from .ppm to %s\n",dstfile);
}
}
// Execute system call
system(str);
free(img);
if(alphaimg!=NULL)
free(alphaimg);
}
I am lost at this point about how to suppress the console that pops up. As we iterate through images via a reference to the dll, many many console windows flash on the screen. Need to stop this from happening.
Help is greatly appreciated.

Answer 1

Try doing:
strcat( str, " > nul" ) // for Windows or
//strcat( str, " > /dev/null" ) // for Unix
system( str )
If it doesn't help then this may help:
#include <string>
#include <ShellAPI.h>
int system_no_output( std::string command )
{
command.insert( 0, "/C " );
SHELLEXECUTEINFOA ShExecInfo = {0};
ShExecInfo.cbSize = sizeof(SHELLEXECUTEINFO);
ShExecInfo.fMask = SEE_MASK_NOCLOSEPROCESS;
ShExecInfo.hwnd = NULL;
ShExecInfo.lpVerb = NULL;
ShExecInfo.lpFile = "cmd.exe";
ShExecInfo.lpParameters = command.c_str();
ShExecInfo.lpDirectory = NULL;
ShExecInfo.nShow = SW_HIDE;
ShExecInfo.hInstApp = NULL;
if( ShellExecuteExA( &ShExecInfo ) == FALSE )
return -1;
WaitForSingleObject( ShExecInfo.hProcess, INFINITE );
DWORD rv;
GetExitCodeProcess( ShExecInfo.hProcess, &rv );
CloseHandle( ShExecInfo.hProcess );
return rv;
}
and replace all your system() calls to system_no_output() ones.

Answer 2

To fully suppress the output, redirect both stdout and stderr:
system("command >nul 2>nul");

Answer 3

Take a look here if you're using C#. The class used in C# is ProcessStartInfo.
In the example in the link, look at the OpenWithStartInfo member function which will minimize the console.
As far as doing this in C++, take a look at the spawn family of functions here.