upper.md

to upper

$ gcc -O3 -Wall -Wextra upper.c -o upper-c

$ rustc -O upper.rs -o upper-rs

$ find /usr/bin/ -type f -exec strings {} + > /tmp/ascii

$ tr [[:lower:]] [[:upper:]] < /tmp/ascii | md5sum
cba0b362aac1eb264e518a33aa2b57eb  -

$ ./upper-c < /tmp/ascii | md5sum
cba0b362aac1eb264e518a33aa2b57eb  -

$ ./upper-rs < /tmp/ascii | md5sum
cba0b362aac1eb264e518a33aa2b57eb  -

$ time tr [[:lower:]] [[:upper:]] < /tmp/ascii > /dev/null

real	0m0.014s
user	0m0.004s
sys	0m0.011s

$ time ./upper-c < /tmp/ascii > /dev/null

real	0m0.013s
user	0m0.004s
sys	0m0.009s

$ time ./upper-rs < /tmp/ascii > /dev/null

real	0m0.008s
user	0m0.000s
sys	0m0.008s

Files

• upper.c:

  #include <ctype.h>
  #include <stdio.h>
  
  int main() {
    char input[4 * 1024];
    size_t len;
    size_t i;
  
    while(!feof(stdin)) {
      len = fread(input, 1, sizeof(input), stdin);
      if(len < 1)
        break;
  
      for(i = 0; i < len; i++) {
        input[i] = toupper(input[i]);
      }
  
      if(fwrite(input, len, 1, stdout) < 1)
        break;
    }
  }

• upper.rs:

  use std::io::{Write, Read};
  
  fn main() {
      let stdout = std::io::stdout();
      let mut output = std::io::BufWriter::new(stdout.lock());
  
      let stdin = std::io::stdin();
      let mut reader = std::io::BufReader::new(stdin.lock());
  
      let mut buf = [0; 4 * 1024];
      while let Ok(len) = reader.read(&mut buf) {
          if len == 0 {
              break;
          }
  
          for byte in &mut buf[..len] {
              *byte = byte.to_ascii_uppercase();
          }
  
          if output.write_all(&buf[..len]).is_err() {
              break;
          }
      }
  }