foo.cc: In function 'int main()':
foo.cc:11:23: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   11 |         for(int i=0; i<strlen(a); i++)
      |                      ~^~~~~~~~~~
foo.cc:13:23: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   13 |         for(int i=0; i<strlen(a); i++)
      |                      ~^~~~~~~~~~
foo.cc:15:31: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   15 |         for(int i=strlen(a); i<strlen(b); i++)
      |                              ~^~~~~~~~~~

Found 10 testcases.
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