Compilare: user.cpp: In function ‘int main()’: user.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( i=0 ; i<strlen(s); i++ ) ^ user.cpp:19:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( j=i+1; j<strlen(s); j++) ^ user.cpp:8:9: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ /tmp/ccChm8xe.o: In function `main': user.cpp:(.text.startup+0x2a): warning: the `gets' function is dangerous and should not be used.