How can we scan a 100 bytes from STDIN in one go in C++

Question

The scanner waits till we enter 100 bytes of data. So if we are redirecting a file into the executable's input, if the file has > 100 bytes of data. I scan it at one go, rather than line by line with fgets() or scanf("%s") etc.

fread() is the function you are looking for. – Kylo Dec 10 '12 at 20:01 — Kylo, Dec 10 '12 at 20:01
Related: Related: http://stackoverflow.com/q/8589425/827263 – Keith Thompson Dec 19 '14 at 22:15 — Keith Thompson, Dec 19 '14 at 22:15

score 3 · Answer 1 · edited Dec 10 '12 at 20:34

You can use fread to read the number of bytes you want, independent of line breaks or other whitespcae:

char buf[100];
size_t bytes_read = fread(buf, 1, 100, stdin);

Note that buf will not be null-terminated. So if you want to printf it, for instance (it needs a null terminated string), you can try the following:

char buf[101];
size_t bytes_read = fread(buf, 1, 100, stdin);
buf[100] = '\0'; // The 101th "cell" of buf will be
                 // the one at index `100` since the
                 // first one is at index `0`.

How can we scan a 100 bytes from STDIN in one go in C++

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