/in/foo.c: In function 'main':
/in/foo.c:9:7: warning: statement with no effect [-Wunused-value]
  s1[i]!='\0';
  ~~~~~^~~~~~
/in/foo.c:12:7: warning: statement with no effect [-Wunused-value]
  s2[j]!='\0';
  ~~~~~^~~~~~