Compilare: user.cpp: In function ‘int main()’: user.cpp:21:23: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[2000005]’ [-Wformat=] fscanf(f, "%s", &a); n = strlen(a); ^ user.cpp:22:23: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[2000005]’ [-Wformat=] fscanf(f, "%s", &b); m = strlen(b); ^ user.cpp:53:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ret.size() && i < 1000; i ++) { ^ user.cpp:21:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%s", &a); n = strlen(a); ^ user.cpp:22:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%s", &b); m = strlen(b); ^