The initial input file can be 3 GB. I have a NASTRAN (Finite Element Analysis software) output file which is pre sorted. The first number in each line represent an element. Element number can be aywhere between 1 to 9999999. They are not consistent either. The example above was just a simplified example. I would not know exact element numbering. So I might have 10 lines starting with element ID 12000. The next element id might be 13450 and I might have 10 lines starting with that number. So I have a huge file, and memory is crucial. I need to have an inteligent algorithm that goes through each line and finds the lines starting with the same number (which I would not know what they are) and put only those ones in to an array. I do not need to create different array for each element number. Once I print the sorted nested array, I can use the same array name and put new lines starting with the same numbers into this array. I am not sure if I am making sense. But thanks for listening.

In reply to Re: Re: How can I read multiple lines starting with the same number and put in to a nested array and print it to a file? by Anonymous Monk
in thread How can I read multiple lines starting with the same number and put in to a nested array and print it to a file? by opolat

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