Compilare: main.cpp: In function 'int main()': main.cpp:25:21: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] a[i][m+1] = NULL; ^~~~ main.cpp:21:10: warning: variable 'c' set but not used [-Wunused-but-set-variable] char c = fgetc(fin); ^ main.cpp:20:31: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d", &n,&m); ^ main.cpp:24:32: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(a[i]+1, m+1, fin); ^