Compilare: user.cpp: In function ‘int main()’: user.cpp:13:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(sir);i++) ^ user.cpp:18:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[i]==c && i<strlen(sir)) ^ user.cpp:7:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("compress.in","r",stdin); ^ user.cpp:8:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("compress.out","w",stdout); ^ user.cpp:9:23: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(sir,N,stdin); ^