A byte stream transfers file data without text-oriented translation. Opened in binary mode, it preserves each byte between the file and the C program, avoiding changes such as platform-specific end-of-line conversion. section 14.6
Use the stream interfaces according to the operation:
- Use fread and fwrite to transfer size*nmemb bytes from the current file position; their return value counts bytes transferred, so a smaller count signals an error. section 14.6
- Use ftell to obtain the byte position and fseek with SEEK_SET or SEEK_CUR to move relative to the file start or current position. section 14.6
- For portable binary handling, open the stream in binary mode; among the previously introduced interfaces, fgetc and fputc handle binary files portably. section 14.6
Comparing a source file byte for byte
A binary-mode program opens __FILE__ with fopen(__FILE__, "rb"), reads it with fread, compares the result using memcmp, writes embedded bytes with fwrite, and reports the input and output counts. section 14.6
size_t fread(void* restrict ptr, size_t size, size_t nmemb,
FILE* restrict stream);
size_t fwrite(void const*restrict ptr, size_t size, size_t nmemb,
FILE* restrict stream);
int fseek(FILE* stream, long int offset, int whence);
long int ftell(FILE* stream);
The core binary-stream API combines byte-counted transfer with explicit file-position control. section 14.6
