/in/foo.cc: In function 'int main()':
/in/foo.cc:17:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<strlen(str1);i++){
               ~^~~~~~~~~~~~~
/in/foo.cc:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<strlen(str1);i++){
               ~^~~~~~~~~~~~~
/in/foo.cc:28:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<strlen(str1);i++){
               ~^~~~~~~~~~~~~