112c112
<       Cerr << "\nError: failure opening " << ampl_col << std::endl;
---
>       Cerr << "\nError: failure opening " << col.c_str() << std::endl;
121c121
< 	Cerr << "\nError: failure reading AMPL col file " << ampl_col 
---
> 	Cerr << "\nError: failure reading AMPL col file " << col.c_str() 
129c129
<       Cerr << "\nError: failure opening " << ampl_row << std::endl;
---
>       Cerr << "\nError: failure opening " << row.c_str() << std::endl;
142c142
< 	Cerr << "\nError: failure reading AMPL row file " << ampl_row 
---
> 	Cerr << "\nError: failure reading AMPL row file " << row.c_str()
