Compilare: user.cpp: In function ‘int main()’: user.cpp:16:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(a[1]);i++) ^ user.cpp:17:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<strlen(a[2]);j++) ^ user.cpp:32:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(a[1]);i++) ^ user.cpp:33:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<strlen(a[2]);j++) ^ user.cpp:35:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(h=0;h<strlen(a[3]);h++) ^