Compilare: user.cpp: In function ‘int main()’: user.cpp:20:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:26:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:32:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(s[i]>='0'&&s[i]<='9'&&i<strlen(s)) ^ user.cpp:43:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:49:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:60:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:66:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:69:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(s[i]>='a'&&s[i]<='z'&&i<strlen(s)) ^ user.cpp:73:19: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] cuv[k]=NULL; ^ user.cpp:76:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(strchr("0123456789",s[i])&&i<strlen(s)) ^