what is fprintf equivalent in qt ?

[Qt embedded developer]

please provide suggestion to convert below c code into qt equivalent code

   FILE *fp;
        int errnum,i=0;

        char ra[50],text[4];

            fp = fopen(SOURCE_FILE,"r");

                if( fp == NULL)
                {
                    printf("the file is now opened.\n");

                    errnum = errno;

                    fprintf(stderr, "Value of errno: %d\n", errno);

                    perror("Error printed by perror");

                    fprintf(stderr, "Error opening file: %s\n", strerror( errnum ));

                }
                else
                {
                    printf("file is now opened\n");

                    /*
                    while( fgets(ra, 50, fp) != NULL)
                    {
                           printf("%s",ra);
                    }
                    */

                   fseek(fp, -543, SEEK_END);
                    //fflush(ra);
                   fgets ( ra, 50, fp );
                    printf("After SEEK_END to -505 :\n%s\n", ra);
                    printf("sizeof(ra) %lu\n",sizeof(ra));

                    for(i;i<10;i++)
                    {
                    printf("%d %c  \n",i,ra[i]);
                    }

                   text[0] = ra[1];
                   text[1] = ra[4];
                   text[2] = ra[7];
                   text[3] = '\0';


                    printf("text ------> %s\n",text);
                    if( fclose(fp) == 0)
                    {
                    printf("data is read successfully \n");
                    printf("the file is now closed\n\n");
                    }

                    printf("Data successfully read from file.c \n");
                    printf("the file is now closed.\n");
                }

[KroMignon]

@Qt-embedded-developer said in what is fprintf equivalent in qt ?:

please provide suggestion to convert below c code into qt equivalent code

Take a look at QFile, QTextStream and QDataStream:
You could start here: https://doc.qt.io/qt-5/qfile.html#details