Compilare: user.cpp: In function ‘int main()’: user.cpp:37:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(a)-1;i++) { ^ user.cpp:43:90: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(!(a[i]>='0'&&a[i]<='9')&&a[i]!=')'&&a[i]!='('&&i<strlen(a)-1) { ^ user.cpp:47:31: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] v[dim]=NULL; ^ user.cpp:35:43: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] while(!feof(f)) fscanf(f,"%c",&a[++i]); ^