The difference between --x and x-- in c language

In C language, --x and x-- are both decrement operators, used to decrement variable x by 1. The difference lies in the time when decrement is performed: --x (prefix decrement): before decrement implement. x-- (post-decrement): executed after decrement. When to use: Use x-- if the variable needs to be used before decrementing, otherwise use --x.

The difference between --x and x-- in C language

In C language, --x and x-- are decrement operators, they both have the same purpose: decrement the value of variable x by 1. However, there are key differences in the timing and context in which they perform the decrement operation.

• --x (preceded decrement)

  --x operator first decrements the value of x by 1, and then in the expression Use this new value.

  Syntax: --x

  Example:

  <code class="c">int x = 5;
  int y = --x; // y 现在为 4，因为 x 已减为 4</code>

• x--( Post-decrement)

  x-- The operator first uses the value of x in the expression and then decrements the value of x by one.

  Grammar: x--

  Example:

  <code class="c">int x = 5;
  int y = x--; // y 现在为 5，因为表达式中使用的 x 值为 5，然后 x 减为 4</code>

Summary of differences:

Operator	Execution time of decrement
-- x (front)	before decrement
x-- (post)	after decrement

When to use:

Generally, use the following rules to decide whether to use --x or x--:

• If you need to decrement If a variable was used before, use x--.
• If you need to use the variable after decrementing, use --x.

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