Compilare: main.cpp: In function 'int main()': main.cpp:34:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<strlen(a);i++) ~^~~~~~~~~~ main.cpp:43:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<strlen(b);i++) ~^~~~~~~~~~ main.cpp:52:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<strlen(c);i++) ~^~~~~~~~~~