{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-05-26T00:16:20.000Z","description":"Problems submitted by members of the MATLAB Central community.","is_default":true,"created_by":161519,"badge_id":null,"featured":false,"trending":false,"solution_count_in_trending_period":0,"trending_last_calculated":"2026-05-26T00:00:00.000Z","image_id":null,"published":true,"community_created":false,"status_id":2,"is_default_group_for_player":false,"deleted_by":null,"deleted_at":null,"restored_by":null,"restored_at":null,"description_opc":null,"description_html":null,"published_at":null},"problems":[{"id":844,"title":"Find files with extension ext in the current directory","description":"List all files with extension 'ext' in the current directory.\r\nReturn a char matrix with the name of files in rows.\r\nReturn 0 if no files.","description_html":"\u003cp\u003eList all files with extension 'ext' in the current directory.\r\nReturn a char matrix with the name of files in rows.\r\nReturn 0 if no files.\u003c/p\u003e","function_template":"function y = filerep(extension)\r\n  y = x;\r\nend","test_suite":"%%\r\naddpath(pwd);\r\nmkdir test\r\ncd test\r\nsave test01.mat\r\nsave test1.mat\r\ny_correct = ['test01.mat';'test1.mat '];\r\nassert(isequal(filerep('mat'),y_correct))\r\n%%\r\ny_correct = 0;\r\nassert(isequal(filerep('bmp'),y_correct))","published":true,"deleted":false,"likes_count":0,"comments_count":4,"created_by":5390,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":37,"test_suite_updated_at":"2012-07-20T07:31:03.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-07-19T10:08:06.000Z","updated_at":"2026-05-26T05:01:05.000Z","published_at":"2012-07-19T10:10:28.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eList all files with extension 'ext' in the current directory. Return a char matrix with the name of files in rows. Return 0 if no files.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"},{"id":1329,"title":"dir with recursive subdirectory search","description":"Write a function that performs a recursive file search.  The input and output\r\nformat can be identical to the dir function. The result should be a struct with the filenames in the field \"name\".\r\n\r\n\r\n_The first solution is from Kelly Kearney (2006)._\r\n","description_html":"\u003cp\u003eWrite a function that performs a recursive file search.  The input and output\r\nformat can be identical to the dir function. The result should be a struct with the filenames in the field \"name\".\u003c/p\u003e\u003cp\u003e\u003ci\u003eThe first solution is from Kelly Kearney (2006).\u003c/i\u003e\u003c/p\u003e","function_template":"function y = subdir(x)\r\n  y = dir(x);\r\nend","test_suite":"%% count files subdirectories\r\nfiles = subdir(fullfile(matlabroot,'java'));\r\nassert(numel(files)\u003e=595 \u0026 isfield(files,'name'))\r\n\r\n%% count text files\r\nfiles = subdir(fullfile(matlabroot,'*.txt'));\r\n[~,~,ext]=cellfun(@fileparts,{files.name},'UniformOutput',false);\r\nassert(numel(files)\u003e=209 \u0026 isfield(files,'name') \u0026 all(strcmp(ext,'.txt')))\r\n\r\n%%\r\nfiles = subdir(fullfile(matlabroot,'toolbox','*.m'));\r\n[~,~,ext] = cellfun(@fileparts,{files.name},'UniformOutput',false);\r\nassert(numel(files)\u003e=15060 \u0026 isfield(files,'name') \u0026 all(strcmp(ext,'.m')))\r\n","published":true,"deleted":false,"likes_count":0,"comments_count":2,"created_by":3105,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":8,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2013-03-09T18:24:49.000Z","updated_at":"2026-05-26T16:51:03.000Z","published_at":"2013-03-09T19:08:55.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eWrite a function that performs a recursive file search. The input and output format can be identical to the dir function. The result should be a struct with the filenames in the field \\\"name\\\".\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:i/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eThe first solution is from Kelly Kearney (2006).\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"problem_search":{"problems":[{"id":844,"title":"Find files with extension ext in the current directory","description":"List all files with extension 'ext' in the current directory.\r\nReturn a char matrix with the name of files in rows.\r\nReturn 0 if no files.","description_html":"\u003cp\u003eList all files with extension 'ext' in the current directory.\r\nReturn a char matrix with the name of files in rows.\r\nReturn 0 if no files.\u003c/p\u003e","function_template":"function y = filerep(extension)\r\n  y = x;\r\nend","test_suite":"%%\r\naddpath(pwd);\r\nmkdir test\r\ncd test\r\nsave test01.mat\r\nsave test1.mat\r\ny_correct = ['test01.mat';'test1.mat '];\r\nassert(isequal(filerep('mat'),y_correct))\r\n%%\r\ny_correct = 0;\r\nassert(isequal(filerep('bmp'),y_correct))","published":true,"deleted":false,"likes_count":0,"comments_count":4,"created_by":5390,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":37,"test_suite_updated_at":"2012-07-20T07:31:03.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-07-19T10:08:06.000Z","updated_at":"2026-05-26T05:01:05.000Z","published_at":"2012-07-19T10:10:28.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eList all files with extension 'ext' in the current directory. Return a char matrix with the name of files in rows. Return 0 if no files.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"},{"id":1329,"title":"dir with recursive subdirectory search","description":"Write a function that performs a recursive file search.  The input and output\r\nformat can be identical to the dir function. The result should be a struct with the filenames in the field \"name\".\r\n\r\n\r\n_The first solution is from Kelly Kearney (2006)._\r\n","description_html":"\u003cp\u003eWrite a function that performs a recursive file search.  The input and output\r\nformat can be identical to the dir function. The result should be a struct with the filenames in the field \"name\".\u003c/p\u003e\u003cp\u003e\u003ci\u003eThe first solution is from Kelly Kearney (2006).\u003c/i\u003e\u003c/p\u003e","function_template":"function y = subdir(x)\r\n  y = dir(x);\r\nend","test_suite":"%% count files subdirectories\r\nfiles = subdir(fullfile(matlabroot,'java'));\r\nassert(numel(files)\u003e=595 \u0026 isfield(files,'name'))\r\n\r\n%% count text files\r\nfiles = subdir(fullfile(matlabroot,'*.txt'));\r\n[~,~,ext]=cellfun(@fileparts,{files.name},'UniformOutput',false);\r\nassert(numel(files)\u003e=209 \u0026 isfield(files,'name') \u0026 all(strcmp(ext,'.txt')))\r\n\r\n%%\r\nfiles = subdir(fullfile(matlabroot,'toolbox','*.m'));\r\n[~,~,ext] = cellfun(@fileparts,{files.name},'UniformOutput',false);\r\nassert(numel(files)\u003e=15060 \u0026 isfield(files,'name') \u0026 all(strcmp(ext,'.m')))\r\n","published":true,"deleted":false,"likes_count":0,"comments_count":2,"created_by":3105,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":8,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2013-03-09T18:24:49.000Z","updated_at":"2026-05-26T16:51:03.000Z","published_at":"2013-03-09T19:08:55.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eWrite a function that performs a recursive file search. The input and output format can be identical to the dir function. The result should be a struct with the filenames in the field \\\"name\\\".\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:i/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eThe first solution is from Kelly Kearney (2006).\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"errors":[],"facets":[[],[{"value":"medium","count":2,"selected":false}]],"term":"tag:\"dir\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}