Compilare: user.cpp: In function ‘int main()’: user.cpp:34:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;i<strlen(str);i++) ^ user.cpp:17:37: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%s %s", substr, str); ^