Compilare: user.cpp: In function ‘int main()’: user.cpp:21:24: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] S[strlen(S)-1] = NULL; ^ user.cpp:22:26: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] st[strlen(st)-1] = NULL; ^ user.cpp:23:26: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] dr[strlen(dr)-1] = NULL; ^ user.cpp:14:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d\n",&T); ^ user.cpp:18:31: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (S , 100000 , f); ^ user.cpp:19:32: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (st , 100000 , f); ^ user.cpp:20:32: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (dr , 100000 , f); ^