Compilare: user.cpp: In function ‘int main()’: user.cpp:20:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<strlen(s);i++) ^ user.cpp:34:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (j<strlen(s)&& s[j]>='0' && s[j]<='9') {ti=ti*10+(s[j]-'0');j++;} ^ user.cpp:18:20: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (s,5000,f1); ^