Final answer:
Formatted input is used to read data with predictable patterns. While standard free-format and fixed-field data are suitable for formatted input, nonstandard data in fixed fields is not, as it lacks predictable patterns and may require special parsing techniques.
Step-by-step explanation:
Formatted input is typically used to read data that follows certain expected patterns or structures. Among the options provided:
- Standard free-format data can certainly be read using formatted input, as 'free-format' indicates that the data is not strictly bound by column positions, but it does follow a recognizable pattern that can be parsed.
- Standard data in fixed fields is ideal for formatted input, since the data fields are aligned at specific positions in a record, which makes it easy to specify the format for input operations.
- Nonstandard data in fixed fields, however, is typically the most challenging for formatted input because although the data may occupy fixed positions within a record, the format might not be consistent or predictable. Formatted input relies on predictable patterns, which nonstandard data typically lacks, making it better suited for unformatted or special parsing techniques.
Therefore, nonstandard data in fixed fields cannot be efficiently read using formatted input.