Compilare: user.cpp: In function ‘int main()’: user.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;i<=strlen(str);i++) ^ user.cpp:16:37: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%s %s", substr, str); ^