What is GNU Fortran?
GNU Fortran, or g77, is designed initially as a free replacement for, or alternative to, the UNIX f77 command. (Similarly, gcc is designed as a replacement for the UNIX cc command.) g77 also is designed to fit in well with the other fine GNU compilers and tools. Sometimes these design goals conflict—in such cases, resolution often is made in favor of fitting in well with Project GNU. These cases are usually identified in the appropriate sections of this manual. As compilers, g77, gcc, and f77 share the following characteristics: • They read a user’s program, stored in a file and containing instructions written in the appropriate language (Fortran, C, and so on). This file contains source code. • They translate the user’s program into instructions a computer can carry out more quickly than it takes to translate the instructions in the first place. These instructions are called machine code—code designed to be efficiently translated and processed by a machine such as a computer. Humans u
