Compilare: user.cpp: In function ‘int nr()’: user.cpp:13:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a[i]>='0'&&a[i]<='9'&&i<strlen(a)) {nr=nr*10+a[i]-'0'; i++;} ^ user.cpp: In function ‘int main()’: user.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(a);i++) { ^ user.cpp:19:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^ user.cpp:22:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%s",a); ^