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PreDecrement
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PreDecrement

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--x

decreases the value of x by 1, returning the new value of x.

Details

Examples

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Basic Examples  (1)Summary of the most common use cases

Decrement the value by one and return the new value:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-bimqpc
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0b8c4ln0q6-eg6pa9
Out[2]=2

Scope  (4)Survey of the scope of standard use cases

Decrement a numerical value:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-3mn70w
Out[1]=1

Decrement a symbolic value:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-2dqqdg
Out[1]=1

Decrement all values in a list:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-boaay
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0b8c4ln0q6-2v76mu
Out[2]=2

The argument to PreDecrement need not be a symbol:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-5axyxt
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/0b8c4ln0q6-s6reew
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0b8c4ln0q6-tck70d
Out[3]=3

Applications  (1)Sample problems that can be solved with this function

Find the first integer below one million with a certain property:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-boq58a
Out[1]=1

Properties & Relations  (4)Properties of the function, and connections to other functions

Decrement and PreDecrement differ in the return value of the operation:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-jd4rit
In[2]:=2
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https://wolfram.com/xid/0b8c4ln0q6-i3im0b
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0b8c4ln0q6-dikf4d
Out[3]=3

PreDecrement is a short form of this assignment:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-5h1xz5
Out[1]=1

PreDecrement is a special case of SubtractFrom:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-lk1x9y
Out[1]=1

Increment and PreIncrement are closely related operations:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-krw5xl
In[2]:=2
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https://wolfram.com/xid/0b8c4ln0q6-hx12qy
Out[2]=2
In[3]:=3
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https://wolfram.com/xid/0b8c4ln0q6-bvd0m5
Out[3]=3

Possible Issues  (1)Common pitfalls and unexpected behavior

A variable to be decremented must have an initial value:

In[1]:=1
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https://wolfram.com/xid/0b8c4ln0q6-xd9vjs
Out[1]=1
Wolfram Research (1988), PreDecrement, Wolfram Language function, https://reference.wolfram.com/language/ref/PreDecrement.html.
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Wolfram Research (1988), PreDecrement, Wolfram Language function, https://reference.wolfram.com/language/ref/PreDecrement.html.

Text

Wolfram Research (1988), PreDecrement, Wolfram Language function, https://reference.wolfram.com/language/ref/PreDecrement.html.

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Wolfram Research (1988), PreDecrement, Wolfram Language function, https://reference.wolfram.com/language/ref/PreDecrement.html.

CMS

Wolfram Language. 1988. "PreDecrement." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/PreDecrement.html.

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Wolfram Language. 1988. "PreDecrement." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/PreDecrement.html.

APA

Wolfram Language. (1988). PreDecrement. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/PreDecrement.html

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Wolfram Language. (1988). PreDecrement. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/PreDecrement.html

BibTeX

@misc{reference.wolfram_2025_predecrement, author="Wolfram Research", title="{PreDecrement}", year="1988", howpublished="\url{https://reference.wolfram.com/language/ref/PreDecrement.html}", note=[Accessed: 26-March-2025 ]}

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@misc{reference.wolfram_2025_predecrement, author="Wolfram Research", title="{PreDecrement}", year="1988", howpublished="\url{https://reference.wolfram.com/language/ref/PreDecrement.html}", note=[Accessed: 26-March-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_predecrement, organization={Wolfram Research}, title={PreDecrement}, year={1988}, url={https://reference.wolfram.com/language/ref/PreDecrement.html}, note=[Accessed: 26-March-2025 ]}

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@online{reference.wolfram_2025_predecrement, organization={Wolfram Research}, title={PreDecrement}, year={1988}, url={https://reference.wolfram.com/language/ref/PreDecrement.html}, note=[Accessed: 26-March-2025 ]}