[The Find It Book
Melvin Amey
The find() method of Array instances returns the first element in the provided array that satisfies the provided testing function. If no values satisfy the testing function, undefined is returned.
A function to execute for each element in the array. It should return a truthy value to indicate a matching element has been found, and a falsy value otherwise. The function is called with the following arguments:
The find() method is an iterative method. It calls a provided callbackFn function once for each element in an array in ascending-index order, until callbackFn returns a truthy value. find() then returns that element and stops iterating through the array. If callbackFn never returns a truthy value, find() returns undefined. Read the iterative methods section for more information about how these methods work in general.
The array argument is useful if you want to access another element in the array, especially when you don't have an existing variable that refers to the array. The following example first uses filter() to extract the positive values and then uses find() to find the first element that is less than its neighbors.
\n The find() method of Array instances returns the first element in the provided array that satisfies the provided testing function.\n If no values satisfy the testing function, undefined is returned.\n
Given a jQuery object that represents a set of DOM elements, the .find() method allows us to search through the descendants of these elements in the DOM tree and construct a new jQuery object from the matching elements. The .find() and .children() methods are similar, except that the latter only travels a single level down the DOM tree.
The first signature for the .find()method accepts a selector expression of the same type that we can pass to the $() function. The elements will be filtered by testing whether they match this selector; all parts of the selector must lie inside of an element on which .find() is called. The expressions allowed include selectors like > p which will find all the paragraphs that are children of the elements in the jQuery object.
The result of this call is a red background on items A, B, 1, 2, 3, and C. Even though item II matches the selector expression, it is not included in the results; only descendants are considered candidates for the match.
Unlike most of the tree traversal methods, the selector expression is required in a call to .find(). If we need to retrieve all of the descendant elements, we can pass in the universal selector '*' to accomplish this.
The find utility shall recursively descend the directory hierarchy from each file specified by path, evaluating aBoolean expression composed of the primaries described in the OPERANDS section for each file encountered.
The find utility shall be able to descend to arbitrary depths in a file hierarchy and shall not fail due to path lengthlimitations (unless a path operand specified by the application exceeds PATH_MAX requirements).
The find utility shall detect infinite loops; that is, entering a previously visited directory that is an ancestor of thelast file encountered. When it detects an infinite loop, find shall write a diagnostic message to standard error and shalleither recover its position in the hierarchy or terminate.
If the primary expression is punctuated by a semicolon, the utility utility_name shall be invoked once for each pathnameand the primary shall evaluate as true if the utility returns a zero value as exit status. A utility_name or argumentcontaining only the two characters "" shall be replaced by the current pathname.
If the primary expression is punctuated by a plus sign, the primary shall always evaluate as true, and the pathnames for whichthe primary is evaluated shall be aggregated into sets. The utility utility_name shall be invoked once for each set ofaggregated pathnames. Each invocation shall begin after the last pathname in the set is aggregated, and shall be completed beforethe find utility exits and before the first pathname in the next set (if any) is aggregated for this primary, but it isotherwise unspecified whether the invocation occurs before, during, or after the evaluations of other primaries. If any invocationreturns a non-zero value as exit status, the find utility shall return a non-zero exit status. An argument containing onlythe two characters "" shall be replaced by the set of aggregated pathnames, with each pathname passed as a separateargument to the invoked utility in the same order that it was aggregated. The size of any set of two or more pathnames shall belimited such that execution of the utility does not cause the system's ARG_MAX limit to be exceeded. If more than one argumentcontaining only the two characters "" is present, the behavior is unspecified.
The -ok primary shall write a prompt to standard error containing at least the utility_name to be invoked and thecurrent pathname. In the POSIX locale, the last non- in the prompt shall be '?'. The exact format used isunspecified.
The bit that is traditionally used for sticky (historically 01000) is specified in the -perm primary using the octalnumber argument form. Since this bit is not defined by this volume of IEEE Std 1003.1-2001, applications must not assumethat it actually refers to the traditional sticky bit.
The descriptions of the '-' modifier on the mode and onum arguments to the -perm primary agreewith historical practice on BSD and System V implementations. System V and BSD documentation both describe it in terms of checkingadditional bits; in fact, it uses the same bits, but checks for having at least all of the matching bits set instead of havingexactly the matching bits set.
The -size operand refers to the size of a file, rather than the number of blocks it may occupy in the file system. Theintent is that the st_size field defined in the System Interfaces volume of IEEE Std 1003.1-2001 should be used,not the st_blocks found in historical implementations. There are at least two reasons for this:
Historical implementations do not modify "" when it appears as a substring of an -exec or -okutility_name or argument string. There have been numerous user requests for this extension, so this volume ofIEEE Std 1003.1-2001 allows the desired behavior. At least one recent implementation does support this feature, butencountered several problems in managing memory allocation and dealing with multiple occurrences of "" in a string whileit was being developed, so it is not yet required behavior.
A feature of SVR4's find utility was the -exec primary's + terminator. This allowed filenames containingspecial characters (especially s) to be grouped together without the problems that occur if such filenames are pipedto xargs. Other implementations have added other ways to get around this problem,notably a -print0 primary that wrote filenames with a null byte terminator. This was considered here, but not adopted. Usinga null terminator meant that any utility that was going to process find's -print0 output had to add a new option toparse the null terminators it would now be reading.
The change invalidates usage like this. Even though the previous standard stated that this usage would work, in practice manydid not support it and the standard developers felt it better to now state that this was not allowable.
Looking for free food in your community? You can easily find a food bank near you by entering your zip code or state. We will provide you with a list of Feeding America partner food banks and their contact information. Connecting with your local food bank is the first step towards getting free food and grocery items.
A food bank is a warehouse that collects and stores food from food donations and food drives.
A food pantry is where people can get free food. A food pantry gets its food from a food bank and gives it directly to people.
FIND is intended for use with languages that use the single-byte character set (SBCS), whereas FINDB is intended for use with languages that use the double-byte character set (DBCS). The default language setting on your computer affects the return value in the following way:
Use start_num to skip a specified number of characters. Using FIND as an example, suppose you are working with the text string "AYF0093.YoungMensApparel". To find the number of the first "Y" in the descriptive part of the text string, set start_num equal to 8 so that the serial-number portion of the text is not searched. FIND begins with character 8, finds find_text at the next character, and returns the number 9. FIND always returns the number of characters from the start of within_text, counting the characters you skip if start_num is greater than 1.
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.
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