Compilare: main.cpp: In function 'int main()': main.cpp:57:40: warning: the address of 'st' will always evaluate as 'true' [-Waddress] while (st && a[i] < st[nrst] && ^ main.cpp:79:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] nrst < strlen(b) ? fprintf(g, "impossible") : fprintf(g, "%s\n", st + 1); ~~~~~^~~~~~~~~~~ main.cpp:29:11: warning: unused variable 'j' [-Wunused-variable] int i,j; ^ main.cpp:33:22: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%s", a); ^ main.cpp:35:22: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%s", b); ^