Basic Examples (2) 

Print expressions from a file:

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Print lines from a file:

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Scope (1) 

Process groups of records in bulk from a file:

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Options (2) 

Print records from a file:

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Specify record separators:

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Applications (1) 

Prematurely end processing a file via Catch and Throw:

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Properties and Relations (3) 

ReadScan[f,file,type] is comparable to Scan[f,ReadList[file,type]], but it may use less memory:

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ReadScan used with Reap and Sow can replicate behavior of ReadList:

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Processing a large file having a simple structure can use a lot of memory if done with Import:

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ReadScan can achieve similar results with significantly less memory:

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If the lines of the file are to be processed, but not stored in the current session, substantially less memory is required:

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Possible Issues (2) 

When processing groups of lines, the final list may include EndOfFile:

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Using Import may be faster:

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Neat Examples (4) 

Download and extract a somewhat large, "nearly-flat" JSON file from USDA FoodData Central:

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Import requires a large amount memory:

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Processing the file line-by-line requires much less memory, and allows for fine-grained control of how each line is processed:

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Clean up by deleting the extracted file:

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