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How can I check if a single character appears in a string?
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You can use string.indexOf('a').
If the char a is present in string :
it returns the the index of the first occurrence of the character in
the character sequence represented by this object, or -1 if the
character does not occur.
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If vs. Switch Speed
Switch statements are typically faster than equivalent if-else-if statements (as e.g. descibed in this article ) due to compiler optimizations.
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Check if object exists in JavaScript
How do I verify the existence of an object in JavaScript?
18 Answers
18
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PHP check whether property exists in object or class
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property_exists( mixed $class , string $property )
if (property_exists($ob, 'a'))
isset( mixed $var [, mixed $... ] )
if (isset($ob->a))
isset() will return false if property is null
Example 1:
$ob->a = null
var_dump(isset($ob->a)); // false
Example 2: ...
Test if a variable is set in bash when using “set -o nounset”
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#!/bin/bash
set -o nounset
VALUE=${WHATEVER:-}
if [ ! -z ${VALUE} ];
then echo "yo"
fi
echo "whatever"
In this case, VALUE ends up being an empty string if WHATEVER is not set. We're using the {parameter:-word} expansion, which you can look up in man bash under "Param...
How do I drop a function if it already exists?
...imple, but how do I preface the creation of a function with a check to see if it already exists? If it exists, I want to drop and re-create it.
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How do I compare two string variables in an 'if' statement in Bash? [duplicate]
I'm trying to get an if statement to work in Bash (using Ubuntu ):
12 Answers
12
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Java String - See if a string contains only numbers and not letters
...ication, and it changes from numbers to letters and such. I have a simple if statement to see if it contains letters or numbers but, something isn't quite working correctly. Here is a snippet.
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Get path of executable
...os.html to select the method is straightforward.
– Clifford
Oct 7 '09 at 15:02
5
So is this what ...
How to check if a variable is not null?
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They are not equivalent. The first will execute the block following the if statement if myVar is truthy (i.e. evaluates to true in a conditional), while the second will execute the block if myVar is any value other than null.
The only values that are not truthy in JavaScript are the following (a...