Shanks asks:

How to read/write bytes from/to a file in C language?

char arr[16];
FILE *fp;
fp=fopen("filename","rb"); // mode can be "rb" for read bytes
and "wb" for write bytes
while(!feof(fp))
{
fread(arr,sizeof(char),strlen(arr),fp); // contents of file are copied
into arr. fwrite has same
syntax.
printf("%s",arr);
}
fclose(fp);