Input en output

• Do not use the PRINT statement, but only the i/o statement keywords READ and WRITE. Never use $*$ as a device number because the device linked to $*$ is machine-dependent.
• File unit numbers should be provided by a generic function or subroutine.
• Use variables for logical unit numbers in READ and WRITE statements.
• Logical unit numbers smaller than 11 are prohibited.
• Always use IOSTAT= instead of ERR= or END= for testing on i/o status.
• Only use a blank for carriage control.
• Create user-friendly error messages including the name of the module where the error occurred.
• Close files which are no longer used.
• Open statements are machine-dependent (see Chapter 10).
• The input should not differentiate between upper case and lower case.
• Input of numerical data should always be free format.