c - fread() returns incorrect data -


i trying read 128kb binary file in chunks of 256 bytes. first 20-40 bytes of 256 bytes seems correct. after data gets corrupted. tried reading file , writing binary file , compared. more half of data corrupted. here code

uint8_t buffer[256] read_bin_file = fopen("vtest.bin", "r"); if (read_bin_file == null) {     printf("unable open file\n");     return false; }  test_bin = fopen("test_file.bin", "w"); if (test_file == null) {     printf("unable open file\n");     return false; }  fflush(stdout);  (i = 0; <=0x1ff; i++) {     file_read_pointer = * 256;     fseek(read_bin_file, file_read_pointer, seek_set);     fread(buffer, 256, 1, read_bin_file);     fseek(test_file, file_read_pointer, seek_set);     fwrite(buffer, 256, 1, test_file);  } 

what missing? when try increase bytes read 256 1024 ( i<0x7f) error seems decrease significantly. file 90% matching

if binary data you're reading , writing, should open files in binary mode read_bin_file = fopen("vtest.bin", "rb");. note "b" in mode. prevents special handling of new line characters.

your fseeks unnecessary, fread , fwrite calls handle you. here "the file position indicator stream advanced number of characters read."


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