Sprintf in QT ?

i need to port some code to qt but i dont find the way to use sprinft yet ... my idea is open a specific .jpg file using a readed str value

this ...

FILE *openingjpg;

char jpgname[256];
sprintf ( jpgname, "/mytempfolder/%s/%s.jpg",str,str);

printf("EL NOMBRE DEL JPG PARA ABRIR ES : %s \n\n",jpgname);

openingjpg=fopen(jpgname,"ab");


anyone give me a help ?
thanks in advance

Code:

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QString jpgname(QString("/mytempfolder/%1/%1.jpg").arg(str));

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