Thankfully trigraphs [0] aren't enabled in compilers such as gcc by default else the following would print "oops":

  #include <stdio.h>
  int main() {
      if ('|' != '??!') {
          printf("ok");
      }
      else {
          printf("oops");
      }
      return 0;
  }

[0] https://en.wikipedia.org/wiki/Digraphs_and_trigraphs