Which function is used to locate the first occurrence of character in any string?

Question

Contents

Inhaltsverzeichnis Show

Example 1: Find index of First Occurrence of Substring
Example 2: Find index of First Occurrence of Substring after a specific position
Definition and Usage
Parameter Values
Technical Details
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Introduction
Example 1: Find index of First Occurrence of Substring
Example 2: Find index of First Occurrence of Substring after a specific position
Summary

To find the position of first occurrence of a string, you can use string.find() method.

index = string.find(substring, start, end)

where string is the string in which you have to find the index of first occurrence of substring. start and end are optional and are starting and ending positions respectively in which substring has to be found.

Example 1: Find index of First Occurrence of Substring

In the following example, we will take a string and try to find the first occurrence of substring prog.

Python Program

string = 'Python programming. Network programming.'
substring = 'prog'

index = string.find(substring)
print(index)

Run

Output

Example 2: Find index of First Occurrence of Substring after a specific position

In the following example, we will take a string and try to find the first occurrence of substring prog after position 12 in the string.

Python Program

string = 'Python programming. Network programming.'
substring = 'prog'
start = 12

index = string.find(substring, start)
print(index)

Run

Output

Now it has found index of the substring that occurred for the first time after start position.

Summary

In this tutorial of Python Examples, we learned how to find the index of substring in a string using str.find() function.

❮ PHP String Reference

Example

Find the position of the first occurrence of "php" inside the string:

<?php
echo strpos("I love php, I love php too!","php");
?>

Try it Yourself »

Definition and Usage

The strpos() function finds the position of the first occurrence of a string inside another string.

Note: The strpos() function is case-sensitive.

Note: This function is binary-safe.

Related functions:

strrpos() - Finds the position of the last occurrence of a string inside another string (case-sensitive)
stripos() - Finds the position of the first occurrence of a string inside another string (case-insensitive)
strripos() - Finds the position of the last occurrence of a string inside another string (case-insensitive)

Syntax

strpos(string,find,start)

Parameter Values

Parameter	Description
string	Required. Specifies the string to search
find	Required. Specifies the string to find
start	Optional. Specifies where to begin the search. If start is a negative number, it counts from the end of the string.

Technical Details

Return Value:	Returns the position of the first occurrence of a string inside another string, or FALSE if the string is not found. Note: String positions start at 0, and not 1.
PHP Version:	4+
Changelog:	PHP 7.1.0 - The start parameter can be a negative number

❮ PHP String Reference

Access for Microsoft 365 Access 2021 Access 2019 Access 2016 Access 2013 Access 2010 Access 2007 More...Less

Returns a Variant (Long) specifying the position of the first occurrence of one string within another.

See some examples

Syntax

InStr ([start, ] string1, string2 [, compare ] )

The InStr function syntax has these arguments:

Argument	Description
start	Optional. Numeric expression that sets the starting position for each search. If omitted, search begins at the first character position. If start contains Null, an error occurs. The start argument is required if compare is specified.
string1	Required. String expression being searched.
string2	Required. String expression sought.
compare	Optional. Specifies the type of string comparison. If compare is Null, an error occurs. If compare is omitted, the OptionCompare setting determines the type of comparison. Specify a valid LCID (LocaleID) to use locale-specific rules in the comparison.

Tip: In Access 2010, the Expression Builder has IntelliSense, so you can see what arguments your expression requires.

Settings

The compare argument settings are:

Constant	Value	Description
vbUseCompareOption	-1	Performs a comparison using the setting of the Option Compare statement.
vbBinaryCompare	0	Performs a binary comparison.
vbTextCompare	1	Performs a textual comparison.
vbDatabaseCompare	2	Microsoft Office Access 2007 only. Performs a comparison based on information in your database.

Return Values

If	InStr returns
string1 is zero-length	0
string1 is Null	Null
string2 is zero-length	start
string2 is Null	Null
string2 is not found	0
string2 is found within string1	Position at which match is found
start > string2	0

Remarks

The InStrB function is used with byte data contained in a string. Instead of returning the character position of the first occurrence of one string within another, InStrB returns the byte position.

Examples

Use the InStr function in an expression You can use InStr wherever you can use expressions. For example, if you want to find the position of the first period (.) in a field that contains IP addresses (named IPAddress), you can use InStr to find it, like so:

InStr(1,[IPAddress],".")

The InStr function examines each value in the IPAddress field and returns the position of the first period. Hence, if the first portion of the IP address is 10., the function returns the value 3.

You can then use other functions, operating on the output of the InStr function, to extract the portion of the IP address that precedes the first period, like so:

Left([IPAddress],(InStr(1,[IPAddress],".")-1))

In this example, InStr(1,[IPAddress],".") returns the position of the first period. Subtracting 1 determines how many characters precede the first period, in this case, 2. The Left function then extracts that many characters from the left portion of the IPAddress field, returning the value 10.

Use InStr in VBA code

Note: Examples that follow demonstrate the use of this function in a Visual Basic for Applications (VBA) module. For more information about working with VBA, select Developer Reference in the drop-down list next to Search and enter one or more terms in the search box.

This example uses the InStr function to return the position of the first occurrence of one string within another.

Dim SearchString, SearchChar, MyPos
SearchString ="XXpXXpXXPXXP"    ' String to search in.
SearchChar = "P"    ' Search for "P".
' A textual comparison starting at position 4. Returns 6.
MyPos = Instr(4, SearchString, SearchChar, 1)    
' A binary comparison starting at position 1. Returns 9.
MyPos = Instr(1, SearchString, SearchChar, 0)
' Comparison is binary by default
' (last argument is omitted).
MyPos = Instr(SearchString, SearchChar)    ' Returns 9.
MyPos = Instr(1, SearchString, "W")    ' Returns 0.