Compilare: user.cpp: In function ‘int main()’: user.cpp:20:18: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(c>='a'&&c<='z'||c>='A'&&c<='Z'||c>='0'&&c<='9'){ ^ user.cpp:20:50: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(c>='a'&&c<='z'||c>='A'&&c<='Z'||c>='0'&&c<='9'){ ^ user.cpp:32:27: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] v[nr][nrc]=NULL; ^ user.cpp:52:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=1;j<=strlen(a[i].ss);j++){ ^ user.cpp:15:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dir.in","r",stdin); ^ user.cpp:16:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dir.out","w",stdout); ^