Compilare: user.cpp: In function ‘void citire()’: user.cpp:21:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<strlen(a);i++) ^ user.cpp:41:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1<strlen(a) && a[i+1]<='9' && a[i+1]>='0' ) ^ user.cpp:17:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expresie2.in","r",stdin); ^ user.cpp:18:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expresie2.out","w",stdout); ^ user.cpp:19:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",a); ^